This should really be using the FSM in libosmocore/laforge/iu_up: take the best
of both sides and integate in the libosmocore FSM implementation, then use it
here.
- in libosmocore, the FSM definition is nicer.
- here, we have correct header checksums.
This patch here also adds RTP header stripping/adding functionality, after
introducing using msgb to pass data around.
Change-Id: Ibc70e0aa00476926dd1f4ea8139c34f31f9cdfa3
