Extended FFmpeg logging with filename/url when possible

Cleaned up decklink_frame::QueryInterface()

Fixed #15. Fork version bump.

Fixed NDI producer access violation

gpu selection moved to <mixer> section of casparcg.config

Fixed empty frame when channel_producer isn't ready - now the first f…

…rame is repeated to pre-fill buffer

changed INFO reported duration to "-1" when unknown (i.e. file is loo…

…ped)

removing irrelevant menu item instead disabling it

fixed playing more than 2 channels on decklink_consumer

added de/re-interlace when up-scaling interlaced video