Add official support for software emulation

[ty-porter]

Adds official support for emulation instead of relying on developer installation of RGBME

This won't be ready to release until RGBME v0.7.0 which will include performance updates to fix the browser adapter memory leaks. That version will also bump the default display adapter to browser for max compatibility across platforms

https://github.com/ty-porter/RGBMatrixEmulator/pull/35

WIP til I can get a bash script created to match the existing setup script for Windows installation

Changes of note:

• Pins dependencies with pipreqs in requirements.txt so we can have an easier job maintaining those
• Also git pulls when cloning rpi-rgb-led-matrix so there's not version mismatches across installations
  • Previously this didn't ever update after initial clone
• The setup script has an -n flag that wasn't documented anywhere, this is changed to -c, --skip-config but retains the same functionality