Remove flac and vorbis extractors
As noted in !49 (merged), there are 3 extractors which "duplicate" the gstreamer extractor: tracker-extract-mp3, tracker-extract-vorbis, and tracker-extract-flac.
The only reason these exist is that they are potentially faster than the GStreamer based extractors. Of course, the downside of these is that they increase the work needed to add and maintain features in Tracker. I think that we should prefer to use the GStreamer extractor in all cases, and if anyone has a requirement that means they need faster performance, they can take responsibility to main the extra 'fast' code paths.
Currently we enable the mp3 extractor by default, and we don't provide any option to enable the ogg or flac extractors.
Edited by Sam Thursfield