Season and episode offsets

Implemented per-show season offset and episode offset for current search queries for differences between the 'scene' and thetvdb.org. Must be manually and personally maintained per show.

I tested with the SickBeard index and the post processor. When one does use sabnzb+ to postprocess, things could get ugly.

More information on google code:
http://code.google.com/p/sickbeard/issues/detail?id=1352

and the forum:
http://sickbeard.com/forums/viewtopic.php?f=8&t=6600