Update AVSwitch.py
Solve some possible GSOD in ChannelSelection.py

Especially when no service is selected in empty bouquets or when some
context options are not available, while there exist a direct key to it
Bring back pip and play in mainscreen in context menu only when required

And also correctly block the direct "color" key
Merge branch 'master' of git://git.code.sf.net/p/openpli/enigma2 into BETA