RLC AM
======

- 36.322 5.4 Re-establishment procedure
  when possible, reassemble RLC SDUs from any byte segments of AMD PDUs
  with SN < VR(MR) in the receiving side, remove RLC headers when doing
  so and deliver all reassembled RLC SDUs to upper layer in ascending order
  of the RLC SN, if not delivered before;

- 36.322 5.2.3 Status reporting
  delay triggering the STATUS report until x < VR(MS) or x >= VR(MR)

- 36.322 5.1.3.2.3 Actions when a RLC data PDU is placed in the reception
  buffer
  [...] and in-sequence byte segments of the AMD PDU with SN = VR(R) [...]

- use SOstart/SOend in NACK reporting, do not NACK full PDU if
  parts of it have been received
