🏗 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/lcd_gpio/display.py

@@ -0,0 +1,45 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome import pins
+from esphome.components import lcd_base
+from esphome.const import CONF_DATA_PINS, CONF_ENABLE_PIN, CONF_RS_PIN, CONF_RW_PIN, CONF_ID, \
+    CONF_UPDATE_INTERVAL
+
+AUTO_LOAD = ['lcd_base']
+
+lcd_gpio_ns = cg.esphome_ns.namespace('lcd_gpio')
+GPIOLCDDisplay = lcd_gpio_ns.class_('GPIOLCDDisplay', lcd_base.LCDDisplay)
+
+
+def validate_pin_length(value):
+    if len(value) != 4 and len(value) != 8:
+        raise cv.Invalid("LCD Displays can either operate in 4-pin or 8-pin mode,"
+                         "not {}-pin mode".format(len(value)))
+    return value
+
+
+CONFIG_SCHEMA = lcd_base.LCD_SCHEMA.extend({
+    cv.GenerateID(): cv.declare_variable_id(GPIOLCDDisplay),
+    cv.Required(CONF_DATA_PINS): cv.All([pins.gpio_output_pin_schema], validate_pin_length),
+    cv.Required(CONF_ENABLE_PIN): pins.gpio_output_pin_schema,
+    cv.Required(CONF_RS_PIN): pins.gpio_output_pin_schema,
+    cv.Optional(CONF_RW_PIN): pins.gpio_output_pin_schema,
+})
+
+
+def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID], config[CONF_UPDATE_INTERVAL])
+    yield lcd_base.setup_lcd_display(var, config)
+    pins_ = []
+    for conf in config[CONF_DATA_PINS]:
+        pins_.append((yield cg.gpio_pin_expression(conf)))
+    cg.add(var.set_data_pins(*pins_))
+    enable = yield cg.gpio_pin_expression(config[CONF_ENABLE_PIN])
+    cg.add(var.set_enable_pin(enable))
+
+    rs = yield cg.gpio_pin_expression(config[CONF_RS_PIN])
+    cg.add(var.set_rs_pin(rs))
+
+    if CONF_RW_PIN in config:
+        rw = yield cg.gpio_pin_expression(config[CONF_RW_PIN])
+        cg.add(var.set_rw_pin(rw))

esphome/components/lcd_gpio/gpio_lcd_display.cpp

@@ -0,0 +1,59 @@
+#include "gpio_lcd_display.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace lcd_gpio {
+
+static const char *TAG = "lcd_gpio";
+
+void GPIOLCDDisplay::setup() {
+  ESP_LOGCONFIG(TAG, "Setting up GPIO LCD Display...");
+  this->rs_pin_->setup();  // OUTPUT
+  this->rs_pin_->digital_write(false);
+  if (this->rw_pin_ != nullptr) {
+    this->rw_pin_->setup();  // OUTPUT
+    this->rw_pin_->digital_write(false);
+  }
+  this->enable_pin_->setup();  // OUTPUT
+  this->enable_pin_->digital_write(false);
+
+  for (uint8_t i = 0; i < (this->is_four_bit_mode() ? 4 : 8); i++) {
+    this->data_pins_[i]->setup();  // OUTPUT
+    this->data_pins_[i]->digital_write(false);
+  }
+  LCDDisplay::setup();
+}
+void GPIOLCDDisplay::dump_config() {
+  ESP_LOGCONFIG(TAG, "GPIO LCD Display:");
+  ESP_LOGCONFIG(TAG, "  Columns: %u, Rows: %u", this->columns_, this->rows_);
+  LOG_PIN("  RS Pin: ", this->rs_pin_);
+  LOG_PIN("  RW Pin: ", this->rw_pin_);
+  LOG_PIN("  Enable Pin: ", this->enable_pin_);
+
+  for (uint8_t i = 0; i < (this->is_four_bit_mode() ? 4 : 8); i++) {
+    ESP_LOGCONFIG(TAG, "  Data Pin %u" LOG_PIN_PATTERN, i, LOG_PIN_ARGS(this->data_pins_[i]));
+  }
+  LOG_UPDATE_INTERVAL(this);
+}
+void GPIOLCDDisplay::write_n_bits(uint8_t value, uint8_t n) {
+  for (uint8_t i = 0; i < n; i++)
+    this->data_pins_[i]->digital_write(value & (1 << i));
+
+  this->enable_pin_->digital_write(true);
+  delayMicroseconds(1);  // >450ns
+  this->enable_pin_->digital_write(false);
+  delayMicroseconds(40);  // >37us
+}
+void GPIOLCDDisplay::send(uint8_t value, bool rs) {
+  this->rs_pin_->digital_write(rs);
+
+  if (this->is_four_bit_mode()) {
+    this->write_n_bits(value >> 4, 4);
+    this->write_n_bits(value, 4);
+  } else {
+    this->write_n_bits(value, 8);
+  }
+}
+
+}  // namespace lcd_gpio
+}  // namespace esphome

esphome/components/lcd_gpio/gpio_lcd_display.h

@@ -0,0 +1,48 @@
+#pragma once
+
+#include "esphome/core/esphal.h"
+#include "esphome/components/lcd_base/lcd_display.h"
+
+namespace esphome {
+namespace lcd_gpio {
+
+class GPIOLCDDisplay : public lcd_base::LCDDisplay {
+ public:
+  GPIOLCDDisplay(uint32_t update_interval) : LCDDisplay(update_interval) {}
+
+  void setup() override;
+  void set_data_pins(GPIOPin *d0, GPIOPin *d1, GPIOPin *d2, GPIOPin *d3) {
+    this->data_pins_[0] = d0;
+    this->data_pins_[1] = d1;
+    this->data_pins_[2] = d2;
+    this->data_pins_[3] = d3;
+  }
+  void set_data_pins(GPIOPin *d0, GPIOPin *d1, GPIOPin *d2, GPIOPin *d3, GPIOPin *d4, GPIOPin *d5, GPIOPin *d6,
+                     GPIOPin *d7) {
+    this->data_pins_[0] = d0;
+    this->data_pins_[1] = d1;
+    this->data_pins_[2] = d2;
+    this->data_pins_[3] = d3;
+    this->data_pins_[4] = d4;
+    this->data_pins_[5] = d5;
+    this->data_pins_[6] = d6;
+    this->data_pins_[7] = d7;
+  }
+  void set_enable_pin(GPIOPin *enable) { this->enable_pin_ = enable; }
+  void set_rs_pin(GPIOPin *rs) { this->rs_pin_ = rs; }
+  void set_rw_pin(GPIOPin *rw) { this->rw_pin_ = rw; }
+  void dump_config() override;
+
+ protected:
+  bool is_four_bit_mode() override { return this->data_pins_[4] == nullptr; }
+  void write_n_bits(uint8_t value, uint8_t n) override;
+  void send(uint8_t value, bool rs) override;
+
+  GPIOPin *rs_pin_{nullptr};
+  GPIOPin *rw_pin_{nullptr};
+  GPIOPin *enable_pin_{nullptr};
+  GPIOPin *data_pins_[8]{nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr};
+};
+
+}  // namespace lcd_gpio
+}  // namespace esphome