🏗 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/climate/climate_traits.cpp

@@ -0,0 +1,57 @@
+#include "climate_traits.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace climate {
+
+bool ClimateTraits::supports_mode(ClimateMode mode) const {
+  switch (mode) {
+    case CLIMATE_MODE_OFF:
+      return true;
+    case CLIMATE_MODE_AUTO:
+      return this->supports_auto_mode_;
+    case CLIMATE_MODE_COOL:
+      return this->supports_cool_mode_;
+    case CLIMATE_MODE_HEAT:
+      return this->supports_heat_mode_;
+    default:
+      return false;
+  }
+}
+bool ClimateTraits::get_supports_current_temperature() const { return supports_current_temperature_; }
+void ClimateTraits::set_supports_current_temperature(bool supports_current_temperature) {
+  supports_current_temperature_ = supports_current_temperature;
+}
+bool ClimateTraits::get_supports_two_point_target_temperature() const { return supports_two_point_target_temperature_; }
+void ClimateTraits::set_supports_two_point_target_temperature(bool supports_two_point_target_temperature) {
+  supports_two_point_target_temperature_ = supports_two_point_target_temperature;
+}
+void ClimateTraits::set_supports_auto_mode(bool supports_auto_mode) { supports_auto_mode_ = supports_auto_mode; }
+void ClimateTraits::set_supports_cool_mode(bool supports_cool_mode) { supports_cool_mode_ = supports_cool_mode; }
+void ClimateTraits::set_supports_heat_mode(bool supports_heat_mode) { supports_heat_mode_ = supports_heat_mode; }
+void ClimateTraits::set_supports_away(bool supports_away) { supports_away_ = supports_away; }
+float ClimateTraits::get_visual_min_temperature() const { return visual_min_temperature_; }
+void ClimateTraits::set_visual_min_temperature(float visual_min_temperature) {
+  visual_min_temperature_ = visual_min_temperature;
+}
+float ClimateTraits::get_visual_max_temperature() const { return visual_max_temperature_; }
+void ClimateTraits::set_visual_max_temperature(float visual_max_temperature) {
+  visual_max_temperature_ = visual_max_temperature;
+}
+float ClimateTraits::get_visual_temperature_step() const { return visual_temperature_step_; }
+int8_t ClimateTraits::get_temperature_accuracy_decimals() const {
+  // use printf %g to find number of digits based on temperature step
+  char buf[32];
+  sprintf(buf, "%.5g", this->visual_temperature_step_);
+  std::string str{buf};
+  size_t dot_pos = str.find('.');
+  if (dot_pos == std::string::npos)
+    return 0;
+
+  return str.length() - dot_pos - 1;
+}
+void ClimateTraits::set_visual_temperature_step(float temperature_step) { visual_temperature_step_ = temperature_step; }
+bool ClimateTraits::get_supports_away() const { return supports_away_; }
+
+}  // namespace climate
+}  // namespace esphome