🏗 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/switch/automation.h

@@ -0,0 +1,95 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/core/automation.h"
+#include "esphome/components/switch/switch.h"
+
+namespace esphome {
+namespace switch_ {
+
+template<typename... Ts> class TurnOnAction : public Action<Ts...> {
+ public:
+  explicit TurnOnAction(Switch *a_switch) : switch_(a_switch) {}
+
+  void play(Ts... x) override {
+    this->switch_->turn_on();
+    this->play_next(x...);
+  }
+
+ protected:
+  Switch *switch_;
+};
+
+template<typename... Ts> class TurnOffAction : public Action<Ts...> {
+ public:
+  explicit TurnOffAction(Switch *a_switch) : switch_(a_switch) {}
+
+  void play(Ts... x) override {
+    this->switch_->turn_off();
+    this->play_next(x...);
+  }
+
+ protected:
+  Switch *switch_;
+};
+
+template<typename... Ts> class ToggleAction : public Action<Ts...> {
+ public:
+  explicit ToggleAction(Switch *a_switch) : switch_(a_switch) {}
+
+  void play(Ts... x) override {
+    this->switch_->toggle();
+    this->play_next(x...);
+  }
+
+ protected:
+  Switch *switch_;
+};
+
+template<typename... Ts> class SwitchCondition : public Condition<Ts...> {
+ public:
+  SwitchCondition(Switch *parent, bool state) : parent_(parent), state_(state) {}
+  bool check(Ts... x) override { return this->parent_->state == this->state_; }
+
+ protected:
+  Switch *parent_;
+  bool state_;
+};
+
+class SwitchTurnOnTrigger : public Trigger<> {
+ public:
+  SwitchTurnOnTrigger(Switch *a_switch) {
+    a_switch->add_on_state_callback([this](bool state) {
+      if (state) {
+        this->trigger();
+      }
+    });
+  }
+};
+
+class SwitchTurnOffTrigger : public Trigger<> {
+ public:
+  SwitchTurnOffTrigger(Switch *a_switch) {
+    a_switch->add_on_state_callback([this](bool state) {
+      if (!state) {
+        this->trigger();
+      }
+    });
+  }
+};
+
+template<typename... Ts> class SwitchPublishAction : public Action<Ts...> {
+ public:
+  SwitchPublishAction(Switch *a_switch) : switch_(a_switch) {}
+  TEMPLATABLE_VALUE(bool, state)
+  void play(Ts... x) override {
+    this->switch_->publish_state(this->state_.value(x...));
+    this->play_next(x...);
+  }
+
+ protected:
+  Switch *switch_;
+};
+
+}  // namespace switch_
+}  // namespace esphome