Zigpy-znp

Global changes
- Support Zigbee groups and multicast requests
- Expose the current Zigbee channel on startup, not just the channel mask.
- Implement LED control. Set it with `led_mode: one of (off, on, blink, flash, toggle)`

Preliminary CC2531 support!
- Network formation and simple commands have been superficially tested
- Validate binary firmware CRCs before firmware flashing with `python -m zigpy_znp.tools.flash_write`
- Skip the 60 second bootloader delay
- Support NVRAM backup/restore. *Warning: don't mix CC2531 backups with ZZH and LAUNCHXL backups. It will not work and you might softlock your device and need to reflash.*

Changes

* Add OTA update support.

Changes

* Read current logical channel on startup. Can be accessed with `app.channel`.
* (Experimental) Allow setting the current logical channel directly in the NIB.
* Allow optional schema parameters for variable-length Z-Stack commands.
* Rename NVRAM commands to `nvram_read` and `nvram_write`.
* Implement flash reading and writing for CC2531:

bash
$ python -m zigpy_znp.tools.flash_read /dev/serial/by-id/radio -o flash.bin
$ python -m zigpy_znp.tools.flash_write /dev/serial/by-id/radio -i flash.bin

Changes

- Add omitted `coloredlogs` dependency for NVRAM backup and restore commands.

Changes

- Add installation instructions for Home Assistant to README.
- Implement NVRAM backup and restore commands.
- Fix network formation bugs.

Changes

- Update README.md with a summary of different chips mentioned Hedda (18)
- Reset the controller on startup to close any pending join requests from a previous run.
- Implement `ZDOCmd.Bind_req`
- Fixed bug where device removal failed halfway through (17)