Summary of changes:
- UE: new thread idx
- UE: Pdcch optim
- UE: slot0 slot1 parallelization
- bugfixes for RLC AM (see gitlab issue 250)
- fix bug "unknown UE_id for rnti"
Note: due to the new UE threading architecture, oaisim and the phy simulators may not work properly anymore. Adaptation in the code has been done, automatic tests seem to pass, but it may not be enough.