Added wma to AUDIO_FILES and m3u to META_FILES
Don't try to calculate statistics for track lengths if the track lengths
are empty
Statistics: dislay the bitrates in kb
Handle exceptions while reading audio file tags
Generate regexp strings for filenames from human readable strings
Refactored parse_track_filename()
Integrated build_re() into parse_track_filename()
Extracted function read_audio_file_tags()
Added default values to track_dict: length, bitrate
Moved reading of tags to module level function
Renamed function x() to parse_directory()
Added more timers
Added collection and statistics of filesize
Fixed display of track names
Collapse ul-lists with Javascript