moved GlobalThread class to GlobalPlayer/thread
refactored vlc player interaction into GlobalPlayer.player module
added more doc strings
added functionality for manipulation of the whole playlist
added individual track manipulation (playlist)
bugfixing: syntax errors
bugfixing: get_status argument type changed, duh >.<
open now prepends the playlist

instead of overwriting the first element
Merge branch 'playlist-backend' into develop
Merge branch 'develop' into playlist-frontend
fix some markup and all controls