FMS: Basic FM skin

TODO:
- Preset/scanning indicator
WPS: Align play mode icon position with FMS

And clean up code a little bit.
SBS: Add play mode icon for FM
WPS: Fix: Wrong play mode icon

If we are in WPS and the play mode is not STOP, PLAY, PAUSE, REWIND,
FORWARD, then a wrong icon was displayed. This case should not be
possible at all, but better handle it correctly.
FMS: Fix signal strength icon position
Update README