427700 - Outgoing extensions that create multiple frames should flush
them in order and atomically.

Modified ExtensionStack to use a Queue and IteratingCallback to make
sure that messages are processed sequentially.
427700 - Outgoing extensions that create multiple frames should flush
them in order and atomically.

Modified DeflateFrameExtension to use a Queue and IteratingCallback to
make sure that frames are iteratively compressed in chunks.
The compression of the next chunk only happen when there is a callback
from the next outgoing layer.
427700 - Outgoing extensions that create multiple frames should flush
them in order and atomically.

Refactored PerMessageDeflateExtension and DeflateFrameExtension
introducing superclass CompressExtension that factors in common
functionalities.
427700 - Outgoing extensions that create multiple frames should flush
them in order and atomically.

Modified FragmentExtension to use a Queue and IteratingCallback to
make sure that frames are iteratively fragmented.
The creation of the next fragment only happens when there is a callback
from the next outgoing layer.