[pvr.tvh] drop invalid packets sooner
[pvr.tvh] return -1 in GetCurrentClientChannel directly

XBMC doesn't even use this API method, it's one of those many things that 
no one has ever bothered to clean up
[pvr.tvh] ignore the stream aspect ratio

This way XBMC will handle changes in aspect ratio (ie. 16:9 <-> 4:3). Should 
fix the issue reported here: http://forum.xbmc.org/showthread.php?tid=170485
[pvr.tvh] - minor corrections to PR#14
Merge remote-tracking branch 'origin/pr/15'
Merge remote-tracking branch 'origin/pr/16'
[pvr.tvh] - bump version to 0.4.0