Decoded VideoFrames construct a VideoFormat
WIP adapting AudioFrame to use new format/layout

This breaks audio even more, for now.
Split Codec into VideoCodec and AudioCodec
Remove dummy streams
Simplify AudioFrame buffer allocation
Codecs use format and layout objects
Abstract Plane from VideoPlane
Properly calculate AudioPlane buffer_size
Decode example PLAYS AUDIO (assuming s16le)
Docs, notes, and disable AudioFifo properties