all the FlexRAN scheduling code is now also handled by the general OAI
scheduling code

- when changing values RC.rrc[i]->configuration should be changed too
- then, RRC_RECONFIGURATION_REQ will pass the changed conf down until PHY
- give warnings at functions that are not implemented

- rename functions
flexran_get_tdd_ack_nack_feedback() -> flexran_get_tdd_ack_nack_feedback_mode()
flexran_get_ue_pmi() -> flexran_get_ue_wpmi()

- defines RCconfig data structures
- adds method to read data
- use it in source files

- lock with mutexes
- don't start ENB_APP task, but Agent directly and wait in case of
  reconfiguration

- {restart,stop}_L1L2() in lte-softmodem.c
- add function start_phy_rrc() in enb_app.{c,h}, accessible from outside
- will be used to restart PHY and RRC when lte-softmodem is restarted

use only one FlexRAN wait function

*Fix the issue with the PDCP UE ID/RNTI management