Add option to conditionally show menu options by a config
Add option to remove VCR scart from main menu (default off)

As most users are using HDMI I suggest most times this option is not
required at all. Especially when it is on the main menu.
Move VRC Scart on main menu option to Videomode (av) menu
Remove obsoleted config.usage.show_vcr_scart

Sorry as I forgot to remove this in the previous commit.
Merge branch 'master' of git://git.code.sf.net/p/openpli/enigma2

Conflicts:
	data/menu.xml
	lib/python/Components/AVSwitch.py