searcher filtering changes

- Filtering of Lossless min/max, Preferred bitrate % and already
downloaded check stops the searcher moving on to torrents if prefer NZB
set (and vice versa). Moved from sort_search_results to new routine

- Preferred bitrate low/high calc not quite right, should be target
size + high %

- Changed to explicitly state
PREFERRED_QUALITY == 1 and added a flag to allow_lossless which is set
if Preferred Bitrate and High Limit and Allow Lossless are all set

- removed unused bitrate from rutracker