* Add constants for sensor device_class
* Add device_class attribute to sensor component
* Add device_class attribute to sensor class
* Add device_class to mhz19 temperature sensor
* Add device_class to sensor in api component
* Add test for device_class of sensor
* Rename DEVICE_CLASS_NONE to DEVICE_CLASS_EMPTY for consistency
* Make optional attributes of sensor component truly optional
Apparently play()/stop() etc. are not meant to be called directly by
users of the class and if they're called directly that would not give
the expected result for the classes that have an empty play().
Make all methods except play_complex, stop_comples and is_running
protected. While there also make RemoteTransmitterActionBase::encode
protected.
* Allow configuration to enable or disable automatic baseline calibration on boot
* Add actions to enable or disable automatic baseline calibration
* Add action to calibrate zero point
## 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).
