🏗 Merge C++ into python codebase (#504)

## Description:

Move esphome-core codebase into esphome (and a bunch of other refactors). See https://github.com/esphome/feature-requests/issues/97

Yes this is a shit ton of work and no there's no way to automate it :( But it will be worth it 👍

Progress:
- Core support (file copy etc): 80%
- Base Abstractions (light, switch): ~50%
- Integrations: ~10%
- Working? Yes, (but only with ported components).

Other refactors:
- Moves all codegen related stuff into a single class: `esphome.codegen` (imported as `cg`)
- Rework coroutine syntax
- Move from `component/platform.py` to `domain/component.py` structure as with HA
- Move all defaults out of C++ and into config validation.
- Remove `make_...` helpers from Application class. Reason: Merge conflicts with every single new integration.
- Pointer Variables are stored globally instead of locally in setup(). Reason: stack size limit.

Future work:
- Rework const.py - Move all `CONF_...` into a conf class (usage `conf.UPDATE_INTERVAL` vs `CONF_UPDATE_INTERVAL`). Reason: Less convoluted import block
- Enable loading from `custom_components` folder.

**Related issue (if applicable):** https://github.com/esphome/feature-requests/issues/97

**Pull request in [esphome-docs](https://github.com/esphome/esphome-docs) with documentation (if applicable):** esphome/esphome-docs#<esphome-docs PR number goes here>

## Checklist:
  - [ ] The code change is tested and works locally.
  - [ ] Tests have been added to verify that the new code works (under `tests/` folder).

If user exposed functionality or configuration variables are added/changed:
  - [ ] Documentation added/updated in [esphomedocs](https://github.com/OttoWinter/esphomedocs).

esphome/components/hmc5883l/hmc5883l.cpp

@@ -0,0 +1,145 @@
+#include "hmc5883l.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace hmc5883l {
+
+static const char *TAG = "hmc5883l";
+static const uint8_t HMC5883L_ADDRESS = 0x1E;
+static const uint8_t HMC5883L_REGISTER_CONFIG_A = 0x00;
+static const uint8_t HMC5883L_REGISTER_CONFIG_B = 0x01;
+static const uint8_t HMC5883L_REGISTER_MODE = 0x02;
+static const uint8_t HMC5883L_REGISTER_DATA_X_MSB = 0x03;
+static const uint8_t HMC5883L_REGISTER_DATA_X_LSB = 0x04;
+static const uint8_t HMC5883L_REGISTER_DATA_Z_MSB = 0x05;
+static const uint8_t HMC5883L_REGISTER_DATA_Z_LSB = 0x06;
+static const uint8_t HMC5883L_REGISTER_DATA_Y_MSB = 0x07;
+static const uint8_t HMC5883L_REGISTER_DATA_Y_LSB = 0x08;
+static const uint8_t HMC5883L_REGISTER_STATUS = 0x09;
+static const uint8_t HMC5883L_REGISTER_IDENTIFICATION_A = 0x0A;
+static const uint8_t HMC5883L_REGISTER_IDENTIFICATION_B = 0x0B;
+static const uint8_t HMC5883L_REGISTER_IDENTIFICATION_C = 0x0C;
+
+void HMC5883LComponent::setup() {
+  ESP_LOGCONFIG(TAG, "Setting up HMC5583L...");
+  uint8_t id[3];
+  if (!this->read_byte(HMC5883L_REGISTER_IDENTIFICATION_A, &id[0]) ||
+      !this->read_byte(HMC5883L_REGISTER_IDENTIFICATION_B, &id[1]) ||
+      !this->read_byte(HMC5883L_REGISTER_IDENTIFICATION_C, &id[2])) {
+    this->error_code_ = COMMUNICATION_FAILED;
+    this->mark_failed();
+    return;
+  }
+
+  if (id[0] != 0x48 || id[1] != 0x34 || id[2] != 0x33) {
+    this->error_code_ = ID_REGISTERS;
+    this->mark_failed();
+    return;
+  }
+
+  uint8_t config_a = 0;
+  // 0b0xx00000 << 5 Sample Averaging - 0b00=1 sample, 0b11=8 samples
+  config_a |= 0b01100000;
+  // 0b000xxx00 << 2 Data Output Rate - 0b100=15Hz
+  config_a |= 0b00010000;
+  // 0b000000xx << 0 Measurement Mode - 0b00=high impedance on load
+  config_a |= 0b00000000;
+  if (!this->write_byte(HMC5883L_REGISTER_CONFIG_A, config_a)) {
+    this->error_code_ = COMMUNICATION_FAILED;
+    this->mark_failed();
+    return;
+  }
+
+  uint8_t config_b = 0;
+  config_b |= this->range_ << 5;
+  if (!this->write_byte(HMC5883L_REGISTER_CONFIG_B, config_b)) {
+    this->error_code_ = COMMUNICATION_FAILED;
+    this->mark_failed();
+    return;
+  }
+
+  uint8_t mode = 0;
+  // Continuous Measurement Mode
+  mode |= 0b00;
+
+  if (!this->write_byte(HMC5883L_REGISTER_MODE, mode)) {
+    this->error_code_ = COMMUNICATION_FAILED;
+    this->mark_failed();
+    return;
+  }
+}
+void HMC5883LComponent::dump_config() {
+  ESP_LOGCONFIG(TAG, "HMC5883L:");
+  LOG_I2C_DEVICE(this);
+  if (this->error_code_ == COMMUNICATION_FAILED) {
+    ESP_LOGE(TAG, "Communication with HMC5883L failed!");
+  } else if (this->error_code_ == ID_REGISTERS) {
+    ESP_LOGE(TAG, "The ID registers don't match - Is this really an HMC5883L?");
+  }
+  LOG_UPDATE_INTERVAL(this);
+
+  LOG_SENSOR("  ", "X Axis", this->x_sensor_);
+  LOG_SENSOR("  ", "Y Axis", this->y_sensor_);
+  LOG_SENSOR("  ", "Z Axis", this->z_sensor_);
+  LOG_SENSOR("  ", "Heading", this->heading_sensor_);
+}
+float HMC5883LComponent::get_setup_priority() const { return setup_priority::DATA; }
+void HMC5883LComponent::update() {
+  uint16_t raw_x, raw_y, raw_z;
+  if (!this->read_byte_16(HMC5883L_REGISTER_DATA_X_MSB, &raw_x) ||
+      !this->read_byte_16(HMC5883L_REGISTER_DATA_Y_MSB, &raw_y) ||
+      !this->read_byte_16(HMC5883L_REGISTER_DATA_Z_MSB, &raw_z)) {
+    this->status_set_warning();
+    return;
+  }
+
+  float mg_per_bit;
+  switch (this->range_) {
+    case HMC5883L_RANGE_88_UT:
+      mg_per_bit = 0.073f;
+      break;
+    case HMC5883L_RANGE_130_UT:
+      mg_per_bit = 0.92f;
+      break;
+    case HMC5883L_RANGE_190_UT:
+      mg_per_bit = 1.22f;
+      break;
+    case HMC5883L_RANGE_250_UT:
+      mg_per_bit = 1.52f;
+      break;
+    case HMC5883L_RANGE_400_UT:
+      mg_per_bit = 2.27f;
+      break;
+    case HMC5883L_RANGE_470_UT:
+      mg_per_bit = 2.56f;
+      break;
+    case HMC5883L_RANGE_560_UT:
+      mg_per_bit = 3.03f;
+      break;
+    case HMC5883L_RANGE_810_UT:
+      mg_per_bit = 4.35f;
+      break;
+    default:
+      mg_per_bit = NAN;
+  }
+
+  // in µT
+  const float x = int16_t(raw_x) * mg_per_bit * 0.1f;
+  const float y = int16_t(raw_y) * mg_per_bit * 0.1f;
+  const float z = int16_t(raw_z) * mg_per_bit * 0.1f;
+
+  float heading = atan2f(0.0f - x, y) * 180.0f / M_PI;
+  ESP_LOGD(TAG, "Got x=%0.02fµT y=%0.02fµT z=%0.02fµT heading=%0.01f°", x, y, z, heading);
+
+  if (this->x_sensor_ != nullptr)
+    this->x_sensor_->publish_state(x);
+  if (this->y_sensor_ != nullptr)
+    this->y_sensor_->publish_state(y);
+  if (this->z_sensor_ != nullptr)
+    this->z_sensor_->publish_state(z);
+  if (this->heading_sensor_ != nullptr)
+    this->heading_sensor_->publish_state(heading);
+}
+
+}  // namespace hmc5883l
+}  // namespace esphome

esphome/components/hmc5883l/hmc5883l.h

@@ -0,0 +1,50 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/sensor/sensor.h"
+#include "esphome/components/i2c/i2c.h"
+
+namespace esphome {
+namespace hmc5883l {
+
+enum HMC5883LRange {
+  HMC5883L_RANGE_88_UT = 0b000,
+  HMC5883L_RANGE_130_UT = 0b001,
+  HMC5883L_RANGE_190_UT = 0b010,
+  HMC5883L_RANGE_250_UT = 0b011,
+  HMC5883L_RANGE_400_UT = 0b100,
+  HMC5883L_RANGE_470_UT = 0b101,
+  HMC5883L_RANGE_560_UT = 0b110,
+  HMC5883L_RANGE_810_UT = 0b111,
+};
+
+class HMC5883LComponent : public PollingComponent, public i2c::I2CDevice {
+ public:
+  HMC5883LComponent(uint32_t update_interval) : PollingComponent(update_interval) {}
+
+  void setup() override;
+  void dump_config() override;
+  float get_setup_priority() const override;
+  void update() override;
+
+  void set_range(HMC5883LRange range) { range_ = range; }
+  void set_x_sensor(sensor::Sensor *x_sensor) { x_sensor_ = x_sensor; }
+  void set_y_sensor(sensor::Sensor *y_sensor) { y_sensor_ = y_sensor; }
+  void set_z_sensor(sensor::Sensor *z_sensor) { z_sensor_ = z_sensor; }
+  void set_heading_sensor(sensor::Sensor *heading_sensor) { heading_sensor_ = heading_sensor; }
+
+ protected:
+  HMC5883LRange range_{HMC5883L_RANGE_130_UT};
+  sensor::Sensor *x_sensor_;
+  sensor::Sensor *y_sensor_;
+  sensor::Sensor *z_sensor_;
+  sensor::Sensor *heading_sensor_;
+  enum ErrorCode {
+    NONE = 0,
+    COMMUNICATION_FAILED,
+    ID_REGISTERS,
+  } error_code_;
+};
+
+}  // namespace hmc5883l
+}  // namespace esphome

esphome/components/hmc5883l/sensor.py

@@ -0,0 +1,71 @@
+# coding=utf-8
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import i2c, sensor
+from esphome.const import CONF_ADDRESS, CONF_ID, CONF_RANGE, CONF_UPDATE_INTERVAL, \
+    ICON_MAGNET, UNIT_MICROTESLA, UNIT_DEGREES, ICON_SCREEN_ROTATION
+
+DEPENDENCIES = ['i2c']
+
+hmc5883l_ns = cg.esphome_ns.namespace('hmc5883l')
+
+CONF_FIELD_STRENGTH_X = 'field_strength_x'
+CONF_FIELD_STRENGTH_Y = 'field_strength_y'
+CONF_FIELD_STRENGTH_Z = 'field_strength_z'
+CONF_HEADING = 'heading'
+
+HMC5883LComponent = hmc5883l_ns.class_('HMC5883LComponent', cg.PollingComponent, i2c.I2CDevice)
+
+HMC5883LRange = hmc5883l_ns.enum('HMC5883LRange')
+HMC5883L_RANGES = {
+    88: HMC5883LRange.HMC5883L_RANGE_88_UT,
+    130: HMC5883LRange.HMC5883L_RANGE_130_UT,
+    190: HMC5883LRange.HMC5883L_RANGE_190_UT,
+    250: HMC5883LRange.HMC5883L_RANGE_250_UT,
+    400: HMC5883LRange.HMC5883L_RANGE_400_UT,
+    470: HMC5883LRange.HMC5883L_RANGE_470_UT,
+    560: HMC5883LRange.HMC5883L_RANGE_560_UT,
+    810: HMC5883LRange.HMC5883L_RANGE_810_UT,
+}
+
+
+def validate_range(value):
+    value = cv.string(value)
+    if value.endswith(u'µT') or value.endswith('uT'):
+        value = value[:-2]
+    return cv.one_of(*HMC5883L_RANGES, int=True)(value)
+
+
+field_strength_schema = sensor.sensor_schema(UNIT_MICROTESLA, ICON_MAGNET, 1)
+heading_schema = sensor.sensor_schema(UNIT_DEGREES, ICON_SCREEN_ROTATION, 1)
+
+CONFIG_SCHEMA = cv.Schema({
+    cv.GenerateID(): cv.declare_variable_id(HMC5883LComponent),
+    cv.Optional(CONF_ADDRESS): cv.i2c_address,
+    cv.Optional(CONF_FIELD_STRENGTH_X): cv.nameable(field_strength_schema),
+    cv.Optional(CONF_FIELD_STRENGTH_Y): cv.nameable(field_strength_schema),
+    cv.Optional(CONF_FIELD_STRENGTH_Z): cv.nameable(field_strength_schema),
+    cv.Optional(CONF_HEADING): cv.nameable(heading_schema),
+    cv.Optional(CONF_UPDATE_INTERVAL, default='60s'): cv.update_interval,
+    cv.Optional(CONF_RANGE, default='130uT'): validate_range,
+}).extend(cv.COMPONENT_SCHEMA).extend(i2c.i2c_device_schema(0x1E))
+
+
+def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID], config[CONF_UPDATE_INTERVAL])
+    yield cg.register_component(var, config)
+    yield i2c.register_i2c_device(var, config)
+
+    cg.add(var.set_range(HMC5883L_RANGES[config[CONF_RANGE]]))
+    if CONF_FIELD_STRENGTH_X in config:
+        sens = yield sensor.new_sensor(config[CONF_FIELD_STRENGTH_X])
+        cg.add(var.set_x_sensor(sens))
+    if CONF_FIELD_STRENGTH_Y in config:
+        sens = yield sensor.new_sensor(config[CONF_FIELD_STRENGTH_Y])
+        cg.add(var.set_y_sensor(sens))
+    if CONF_FIELD_STRENGTH_Z in config:
+        sens = yield sensor.new_sensor(config[CONF_FIELD_STRENGTH_Z])
+        cg.add(var.set_z_sensor(sens))
+    if CONF_HEADING in config:
+        sens = yield sensor.new_sensor(config[CONF_HEADING])
+        cg.add(var.set_heading_sensor(sens))