* WIP commit
* deficient handling
* Add missing ProvisionalAllocatePrepare
* adjust state on track removal
* Increase test timeout
* - Add comments about cooperative routines
- Take down transition if available in cooperative scheme
- Use layer comparison when taking down transition. Because of when the
bitrate is measured, it is not always guaranteed bandwidthDelta is -ve
when moving down.
- Do not add track to stream allocator till bind.
* make comment better
* a bit more clear comments
* Use OnBind on subscribed track
