* Use media payload size in scoring.
Subtract out header bytes when calculating score.
This does not seem to affect the score (under perfect conditions),
but, using header bytes will inflate the bit rate and
will affect scoring.
* Add header bytes to ToProto
* protocol pointer
* fix test
* Remove `Head` field from `ExtPacket` structure.
Although we do not intend to, but if packets get out-of-order
in the forwarding path (maybe reading in multiple goroutines
or using some worker pool to distribute packets), the `Head`
indicator could lead to wrong behaviour. It is possible that
at the receiver, the order is
- Seq Num N, Head = true
- N + 1, Head = true
If the forwarding path sees `N + 1` first, the Head flag
when it sees `N` packet is incorrect and will lead to incorrect
behaviour.
The alternative check is very simple. So, remove `Head` flag.
* Remove unused field
