Improve Human-Computer Interation of PVR EPG

Hello All,

This pull request aims to resolve the following feature suggestion/request:

http://forum.xbmc.org/showthread.php?tid=154675&pid=1383179#pid1383179.

Please see commit notes and diff stats for further details.

It is only a small amount of code, but strongly believe it corrects what the user expects when navigating the PVR EPG (tested as working on all EPG views).  

I trust all is in order,

Many thanks,
Guy.