Add SenseHat emulator support

[nunnatsa]

Type: enhancement

Description

The SenseHat Emulator is a cross platform python based emulation of the raspberry-pi sense hat device.

It would be very nice if the PiHatDraw application will communicate with this emulator, allowing users and developers to use the piHatDraw application even if they don't have access to the relevant hardware (the sense hat or a raspberry pi computer).

Suggestion

build a Hat interface, then on initialization, try to find the senseHat. If not exists, try to find the emulator. Then build the relevant instance - emulator controller or real sense hat controller. The rest of the application should know nothing about it - it will use the interface and the channels.

Additional information:

• SenseHat Emulator documentation - https://sense-emu.readthedocs.io/en/v1.1/install.html
• SenseHar Emulator source code - https://github.com/astro-pi/python-sense-emu