Remove transient ByteBuffer from Sender
Remove transient ByteBuffer from Sender

Kryo wasn't reconstructing the object correctly due to the transient field. It
was remaining empty because there wasn't anywhere to re-wrap the buffer during
Kryo's deserialization process. This change removes the field altogether,
replacing it with wrapping the buffer everywhere it is used (a silly amount of
allocations, I know).

I plan on reducing the allocations once the dust settles.

whymarrh/RxBroadcast,RxBroadcast/RxBroadcast,RxBroadcast/RxBroadcast,whymarrh/RxBroadcast,RxBroadcast/RxBroadcast,RxBroadcast/RxBroadcast