Made audio_candence sequences mean the number of samples per channel instead of the number of samples for *both* channels

#6

Fixed bug where we give too few samples to the decklink driver each time RenderAudioSamples() is called (constant rate of 50 calls per second) when the video format has a frame rate > 50 like 59.94 and 60

#22
Merge branch 'master' of https://github.com/CasparCG/Server