🏗 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/monochromatic/light.py

@@ -0,0 +1,18 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import light, output
+from esphome.const import CONF_OUTPUT_ID, CONF_OUTPUT
+
+monochromatic_ns = cg.esphome_ns.namespace('monochromatic')
+MonochromaticLightOutput = monochromatic_ns.class_('MonochromaticLightOutput', light.LightOutput)
+
+CONFIG_SCHEMA = cv.nameable(light.BRIGHTNESS_ONLY_LIGHT_SCHEMA.extend({
+    cv.GenerateID(CONF_OUTPUT_ID): cv.declare_variable_id(MonochromaticLightOutput),
+    cv.Required(CONF_OUTPUT): cv.use_variable_id(output.FloatOutput),
+}))
+
+
+def to_code(config):
+    out = yield cg.get_variable(config[CONF_OUTPUT])
+    var = cg.new_Pvariable(config[CONF_OUTPUT_ID], out)
+    yield light.register_light(var, config)

esphome/components/monochromatic/monochromatic_light_output.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/output/float_output.h"
+#include "esphome/components/light/light_output.h"
+
+namespace esphome {
+namespace monochromatic {
+
+class MonochromaticLightOutput : public light::LightOutput {
+ public:
+  MonochromaticLightOutput(output::FloatOutput *output) : output_(output) {}
+  light::LightTraits get_traits() override {
+    auto traits = light::LightTraits();
+    traits.set_supports_brightness(true);
+    return traits;
+  }
+  void write_state(light::LightState *state) override {
+    float bright;
+    state->current_values_as_brightness(&bright);
+    this->output_->set_level(bright);
+  }
+
+ protected:
+  output::FloatOutput *output_;
+};
+
+}  // namespace monochromatic
+}  // namespace esphome