🏗 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/speed/fan/__init__.py

@@ -0,0 +1,32 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import fan, output
+from esphome.const import CONF_OSCILLATION_OUTPUT, CONF_OUTPUT, \
+    CONF_OUTPUT_ID, CONF_SPEED, CONF_LOW, CONF_MEDIUM, CONF_HIGH
+from .. import speed_ns
+
+SpeedFan = speed_ns.class_('SpeedFan', cg.Component)
+
+CONFIG_SCHEMA = cv.nameable(fan.FAN_SCHEMA.extend({
+    cv.GenerateID(CONF_OUTPUT_ID): cv.declare_variable_id(SpeedFan),
+    cv.Required(CONF_OUTPUT): cv.use_variable_id(output.FloatOutput),
+    cv.Optional(CONF_OSCILLATION_OUTPUT): cv.use_variable_id(output.BinaryOutput),
+    cv.Optional(CONF_SPEED, default={}): cv.Schema({
+        cv.Optional(CONF_LOW, default=0.33): cv.percentage,
+        cv.Optional(CONF_MEDIUM, default=0.66): cv.percentage,
+        cv.Optional(CONF_HIGH, default=1.0): cv.percentage,
+    }),
+}).extend(cv.COMPONENT_SCHEMA))
+
+
+def to_code(config):
+    output_ = yield cg.get_variable(config[CONF_OUTPUT])
+    state = yield fan.create_fan_state(config)
+    var = cg.new_Pvariable(config[CONF_OUTPUT_ID], state, output_)
+    yield cg.register_component(var, config)
+    speeds = config[CONF_SPEED]
+    cg.add(var.set_speeds(speeds[CONF_LOW], speeds[CONF_MEDIUM], speeds[CONF_HIGH]))
+
+    if CONF_OSCILLATION_OUTPUT in config:
+        oscillation_output = yield cg.get_variable(config[CONF_OSCILLATION_OUTPUT])
+        cg.add(var.set_oscillation(oscillation_output))

esphome/components/speed/fan/speed_fan.cpp

@@ -0,0 +1,53 @@
+#include "speed_fan.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace speed {
+
+static const char *TAG = "speed.fan";
+
+void SpeedFan::dump_config() {
+  ESP_LOGCONFIG(TAG, "Fan '%s':", this->fan_->get_name().c_str());
+  if (this->fan_->get_traits().supports_oscillation()) {
+    ESP_LOGCONFIG(TAG, "  Oscillation: YES");
+  }
+}
+void SpeedFan::setup() {
+  auto traits = fan::FanTraits(this->oscillating_ != nullptr, true);
+  this->fan_->set_traits(traits);
+  this->fan_->add_on_state_callback([this]() { this->next_update_ = true; });
+}
+void SpeedFan::loop() {
+  if (!this->next_update_) {
+    return;
+  }
+  this->next_update_ = false;
+
+  {
+    float speed = 0.0f;
+    if (this->fan_->state) {
+      if (this->fan_->speed == fan::FAN_SPEED_LOW)
+        speed = this->low_speed_;
+      else if (this->fan_->speed == fan::FAN_SPEED_MEDIUM)
+        speed = this->medium_speed_;
+      else if (this->fan_->speed == fan::FAN_SPEED_HIGH)
+        speed = this->high_speed_;
+    }
+    ESP_LOGD(TAG, "Setting speed: %.2f", speed);
+    this->output_->set_level(speed);
+  }
+
+  if (this->oscillating_ != nullptr) {
+    bool enable = this->fan_->oscillating;
+    if (enable) {
+      this->oscillating_->turn_on();
+    } else {
+      this->oscillating_->turn_off();
+    }
+    ESP_LOGD(TAG, "Setting oscillation: %s", ONOFF(enable));
+  }
+}
+float SpeedFan::get_setup_priority() const { return setup_priority::DATA; }
+
+}  // namespace speed
+}  // namespace esphome

esphome/components/speed/fan/speed_fan.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/output/binary_output.h"
+#include "esphome/components/output/float_output.h"
+#include "esphome/components/fan/fan_state.h"
+
+namespace esphome {
+namespace speed {
+
+class SpeedFan : public Component {
+ public:
+  SpeedFan(fan::FanState *fan, output::FloatOutput *output) : fan_(fan), output_(output) {}
+  void setup() override;
+  void loop() override;
+  void dump_config() override;
+  float get_setup_priority() const override;
+  void set_oscillating(output::BinaryOutput *oscillating) { this->oscillating_ = oscillating; }
+  void set_speeds(float low, float medium, float high) {
+    this->low_speed_ = low;
+    this->medium_speed_ = medium;
+    this->high_speed_ = high;
+  }
+
+ protected:
+  fan::FanState *fan_;
+  output::FloatOutput *output_;
+  output::BinaryOutput *oscillating_{nullptr};
+  float low_speed_{};
+  float medium_speed_{};
+  float high_speed_{};
+  bool next_update_{true};
+};
+
+}  // namespace speed
+}  // namespace esphome