"library" thread
- Implement filescanner as a library_source
- Add library source implementation for spotify
- Move process_media_info to library with small adjustments:
- Remove dependency to F_SCAN_TYPE defines
- Pass data_kind as parameter
- Pass media_kind and compilation as parameter if a source forces a
specific value for these
- Move declaration of scan_ffmpeg to library; add
library_add_playlist_info to library