🏗 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).

platformio.ini

@@ -0,0 +1,48 @@
+; This file is so that the C++ files in this repo
+; can be edited with IDEs like VSCode or CLion
+; with the platformio system
+; It's *not* used during runtime.
+
+[platformio]
+env_default = livingroom8266
+src_dir = .
+include_dir = include
+
+[common]
+lib_deps =
+    AsyncTCP@1.0.3
+    AsyncMqttClient@0.8.2
+    ArduinoJson-esphomelib@5.13.3
+    ESP Async WebServer@1.1.1
+    FastLED@3.2.0
+    NeoPixelBus@2.4.1
+    ESPAsyncTCP@1.2.0
+build_flags =
+    -Wno-reorder
+    -DUSE_WEB_SERVER
+    -DUSE_FAST_LED_LIGHT
+    -DUSE_NEO_PIXEL_BUS_LIGHT
+    -DDONT_STORE_LOG_STR_IN_FLASH
+    -DCLANG_TIDY
+; Don't use FlashStringHelper for debug builds because CLion freaks out for all
+; log messages
+src_filter = +<esphome>
+
+[env:livingroom32]
+platform = espressif32@1.6.0
+board = nodemcu-32s
+framework = arduino
+lib_deps = ${common.lib_deps}
+build_flags = ${common.build_flags} -DUSE_ETHERNET
+src_filter = ${common.src_filter} +<tests/livingroom32.cpp>
+
+[env:livingroom8266]
+platform = espressif8266@1.8.0
+board = nodemcuv2
+framework = arduino
+lib_deps =
+    ${common.lib_deps}
+    ESP8266WiFi
+    Hash
+build_flags = ${common.build_flags} -DESPHOME_LOG_LEVEL=6
+src_filter = ${common.src_filter} +<tests/livingroom8266.cpp>