File filters in open dialogs
We should have default filters in the open dialogs, like
- All files
- Sound Files ( .mp3, .ogg, .wav, .m4a, .m4p)
- Video Files ( .avi, .mkv, .mov, .mpg, .m2v, etc)
- Subtitle Files ( .idx, .sub, .utf, .srt)
This should probably be centralized somewhere in include/ (in vlc_interface.h ?)