Fixed an error where the scanner failed to update.
A few minor changes to the AudioScanner flag byte.
AudioScan sets action to Skip for existing tracks if remove or update is disabled.
An AudioScanner with parseAdd, parseUpdate and removeDeadFiles all set to false will not scan HDD for files - all existing files are handled with Skip action.
Track is now internally mutable, (for #2).
Added ToString methods for library base classes.
Implemented an UpdateTrack method on Library, which closes #2.
AudioScan adds to error counter on case AddError and UpdateError.
Implemented generic search methods for IEnumerable<T> collections.
Rearranged SearchMethods argument for all Search methods.
Added Search-conversion methods, for implementing Playlist search.
Implemented playlist search using track-converter.
Refactored a splitString method for Search methods.
Renamed the "test" method to "compareElement".
Added additional search methods for IEnumerable<Track>.