[pvr] unify channel info settings + show channel info after channel switch from within channel osd

This unifies the settings 'pvrmenu.infoswitch', 'pvrmenu.infotimeout', 'pvrmenu.infotime' to one new setting 'pvrmenu.displaychannelinfo' which holds the option 'Off' and '1 sec' to '15 sec'.

This also add the behavior for showing the channel info if you switch a channel from within the channel osd.

Both were discussed at http://forum.xbmc.org/showthread.php?tid=200000

@opdenkamp or @Jalle19 for a quick look.
if your channel switch time is 6-9 secs, it makes sense :)