- plugins: Fix assignment of prefered keys

New keyword in plugin.cfg: key=<key>
* key=red
* key=green
* key=yellow
* key=blue
* key=auto

If entry is missing key is auto-assigned
- user_menue: allow colored keys from plugin.cfg
Merge remote-tracking branch 'cool-cst-next/cst-next'

Conflicts:
	src/gui/user_menue.cpp