Improve Human-Computer Interation of PVR EPG

Furter to the feature request:
http://forum.xbmc.org/showthread.php?tid=154675&pid=1383179#pid1383179
This commit aims to address the second change request therein.  Pressing
the "OK" button over an EPG entry that is currently playing (i.e. Live),
the default behaviour switches straight to that channel and clears the EPG. However, EPG
entries that are not currently playing (i.e. future timeline entries)
then the behaviour, "Programme Info" pop-up context menu appears to
give the user the option to set a timer for this future event.
Merge branch 'hci_epg' of https://github.com/guyrichie/xbmc into hci_epg