[rbp] Remove PiAudio engine
[rbp] Add PiAudio sink
[rbp] Allow paplayer to be enabled on Pi
[rbp/omxplayer] Suspend AE when playing audio
[rbp/omxplayer] Remove visualisation support

This is now handled by paplayer
Revert "[rbp/omxplayer] Ignore video stream in audio filetypes"

This reverts commit ca5119d8bd73a632e6006e77cba7f59a37c3dbb2.
fixed: Handle (non) URL encoding and forward backward slashes properly for path substitution
fixed: Copying of file(names) from non-URL to URL encoded filesystem
changed: Extend path substitude unit test
[rbp/gui] Add switch between higher and lower quality textures

To save memory we default to 16bpp textures,
but provide a GUI option to increase that to 32bpp.
[rbp/gui] Add switch to remove GUI 720p limit