🏗 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/uln2003/stepper.py

@@ -0,0 +1,41 @@
+from esphome import pins
+from esphome.components import stepper
+import esphome.config_validation as cv
+import esphome.codegen as cg
+from esphome.const import CONF_ID, CONF_PIN_A, CONF_PIN_B, CONF_PIN_C, CONF_PIN_D, \
+    CONF_SLEEP_WHEN_DONE, CONF_STEP_MODE
+
+
+uln2003_ns = cg.esphome_ns.namespace('uln2003')
+ULN2003StepMode = uln2003_ns.enum('ULN2003StepMode')
+
+STEP_MODES = {
+    'FULL_STEP': ULN2003StepMode.ULN2003_STEP_MODE_FULL_STEP,
+    'HALF_STEP': ULN2003StepMode.ULN2003_STEP_MODE_HALF_STEP,
+    'WAVE_DRIVE': ULN2003StepMode.ULN2003_STEP_MODE_WAVE_DRIVE,
+}
+
+ULN2003 = uln2003_ns.class_('ULN2003', stepper.Stepper, cg.Component)
+
+CONFIG_SCHEMA = stepper.STEPPER_SCHEMA.extend({
+    cv.Required(CONF_ID): cv.declare_variable_id(ULN2003),
+    cv.Required(CONF_PIN_A): pins.gpio_output_pin_schema,
+    cv.Required(CONF_PIN_B): pins.gpio_output_pin_schema,
+    cv.Required(CONF_PIN_C): pins.gpio_output_pin_schema,
+    cv.Required(CONF_PIN_D): pins.gpio_output_pin_schema,
+    cv.Optional(CONF_SLEEP_WHEN_DONE, default=False): cv.boolean,
+    cv.Optional(CONF_STEP_MODE, default='FULL_STEP'): cv.one_of(*STEP_MODES, upper=True, space='_')
+}).extend(cv.COMPONENT_SCHEMA)
+
+
+def to_code(config):
+    pin_a = yield cg.gpio_pin_expression(config[CONF_PIN_A])
+    pin_b = yield cg.gpio_pin_expression(config[CONF_PIN_B])
+    pin_c = yield cg.gpio_pin_expression(config[CONF_PIN_C])
+    pin_d = yield cg.gpio_pin_expression(config[CONF_PIN_D])
+    var = cg.new_Pvariable(config[CONF_ID], pin_a, pin_b, pin_c, pin_d)
+    yield cg.register_component(var, config)
+    yield stepper.register_stepper(var, config)
+
+    cg.add(var.set_sleep_when_done(config[CONF_SLEEP_WHEN_DONE]))
+    cg.add(var.set_step_mode(STEP_MODES[config[CONF_STEP_MODE]]))

esphome/components/uln2003/uln2003.cpp

@@ -0,0 +1,97 @@
+#include "uln2003.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace uln2003 {
+
+static const char *TAG = "uln2003.stepper";
+
+void ULN2003::setup() {
+  this->pin_a_->setup();
+  this->pin_b_->setup();
+  this->pin_c_->setup();
+  this->pin_d_->setup();
+  this->loop();
+}
+void ULN2003::loop() {
+  bool at_target = this->has_reached_target();
+  if (at_target) {
+    this->high_freq_.stop();
+
+    if (this->sleep_when_done_) {
+      this->pin_a_->digital_write(false);
+      this->pin_b_->digital_write(false);
+      this->pin_c_->digital_write(false);
+      this->pin_d_->digital_write(false);
+      // do not write pos
+      return;
+    }
+  } else {
+    this->high_freq_.start();
+
+    int dir = this->should_step_();
+    this->current_uln_pos_ += dir;
+  }
+
+  this->write_step_(this->current_uln_pos_);
+}
+void ULN2003::dump_config() {
+  ESP_LOGCONFIG(TAG, "ULN2003:");
+  LOG_PIN("  Pin A: ", this->pin_a_);
+  LOG_PIN("  Pin B: ", this->pin_b_);
+  LOG_PIN("  Pin C: ", this->pin_c_);
+  LOG_PIN("  Pin D: ", this->pin_d_);
+  ESP_LOGCONFIG(TAG, "  Sleep when done: %s", YESNO(this->sleep_when_done_));
+  const char *step_mode_s = "";
+  switch (this->step_mode_) {
+    case ULN2003_STEP_MODE_FULL_STEP:
+      step_mode_s = "FULL STEP";
+      break;
+    case ULN2003_STEP_MODE_HALF_STEP:
+      step_mode_s = "HALF STEP";
+      break;
+    case ULN2003_STEP_MODE_WAVE_DRIVE:
+      step_mode_s = "WAVE DRIVE";
+      break;
+  }
+  ESP_LOGCONFIG(TAG, "  Step Mode: %s", step_mode_s);
+}
+void ULN2003::write_step_(int32_t step) {
+  int32_t n = this->step_mode_ == ULN2003_STEP_MODE_HALF_STEP ? 8 : 4;
+  auto i = static_cast<uint32_t>((step % n + n) % n);
+  uint8_t res = 0;
+
+  switch (this->step_mode_) {
+    case ULN2003_STEP_MODE_FULL_STEP: {
+      // AB, BC, CD, DA
+      res |= 1 << i;
+      res |= 1 << ((i + 1) % 4);
+      break;
+    }
+    case ULN2003_STEP_MODE_HALF_STEP: {
+      // A, AB, B, BC, C, CD, D, DA
+      if (i == 0 || i == 2 || i == 7)
+        res |= 1 << 0;
+      if (i == 1 || i == 2 || i == 3)
+        res |= 1 << 1;
+      if (i == 3 || i == 4 || i == 5)
+        res |= 1 << 2;
+      if (i == 5 || i == 6 || i == 7)
+        res |= 1 << 3;
+      break;
+    }
+    case ULN2003_STEP_MODE_WAVE_DRIVE: {
+      // A, B, C, D
+      res |= 1 << i;
+      break;
+    }
+  }
+
+  this->pin_a_->digital_write((res >> 0) & 1);
+  this->pin_b_->digital_write((res >> 1) & 1);
+  this->pin_c_->digital_write((res >> 2) & 1);
+  this->pin_d_->digital_write((res >> 3) & 1);
+}
+
+}  // namespace uln2003
+}  // namespace esphome

esphome/components/uln2003/uln2003.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/core/esphal.h"
+#include "esphome/components/stepper/stepper.h"
+
+namespace esphome {
+namespace uln2003 {
+
+enum ULN2003StepMode {
+  ULN2003_STEP_MODE_FULL_STEP,
+  ULN2003_STEP_MODE_HALF_STEP,
+  ULN2003_STEP_MODE_WAVE_DRIVE,
+};
+
+class ULN2003 : public stepper::Stepper, public Component {
+ public:
+  ULN2003(GPIOPin *pin_a, GPIOPin *pin_b, GPIOPin *pin_c, GPIOPin *pin_d)
+      : pin_a_(pin_a), pin_b_(pin_b), pin_c_(pin_c), pin_d_(pin_d) {}
+
+  void setup() override;
+  void loop() override;
+  void dump_config() override;
+  float get_setup_priority() const override { return setup_priority::HARDWARE; }
+  void set_sleep_when_done(bool sleep_when_done) { this->sleep_when_done_ = sleep_when_done; }
+  void set_step_mode(ULN2003StepMode step_mode) { this->step_mode_ = step_mode; }
+
+ protected:
+  void write_step_(int32_t step);
+
+  bool sleep_when_done_{false};
+  GPIOPin *pin_a_;
+  GPIOPin *pin_b_;
+  GPIOPin *pin_c_;
+  GPIOPin *pin_d_;
+  ULN2003StepMode step_mode_{ULN2003_STEP_MODE_FULL_STEP};
+  HighFrequencyLoopRequester high_freq_;
+  int32_t current_uln_pos_{0};
+};
+
+}  // namespace uln2003
+}  // namespace esphome