Made Indexer searching for special episodes be very explicit
Added SpecialEpisodeSearchCriteria criteria to handle special episode search queries
Added method NzbSearchService.SearchSpecial()
Simplified code to just use fuzzy searching for special episodes on season 0. Can extend later for more general searching if needed.
Added ParsedEpisodeInfo.IsPossibleSpecialEpisode() that will determine if a special episode search is required