ref #1627 [Sometimes video playback stops]
ref #1627 [Sometimes video playback stops]

http://redmine.named-data.net/issues/1627
--
- fixed logic for skipping frames: previously, frame could be marked to
be skipped at the acquireSlot call with no respect for the frame type.
this sometimes caused skipping key frames - and NeedKey buffer event
could not be triggered anymore.
fixed by making one frame release point - in releaseSlot call

remap/ndnrtc,remap/ndnrtc,remap/ndnrtc,remap/ndnrtc