Updated handling of DL_config and Tx_req pdus in phy_stub_UE to be compliant with nfapi callback functions

Added MAC level state variable for the UE and control mechanisms to ensure the correct operation of the UE MAC state machine.

Added remaining fill_harq indication functions + the functionality to handle ul_config request pdus arriving from nfapi-vnf: trigger the appropriate UE_MAC and fill_indication functions to prepare the UL_indications which will be put into the socket for transfer back to vnf. Main changes within phy_stub_UE().

Added fill functions for rx, crc and sr indications in phy_stub_UE. These functions will be getting called directly from the MAC layer of the UE. Rest of fill functions remain to be added.

- UE_id 0 is for rnti 65535 (sib)
- UE_id 1 is for rnti 65534 (this is a hack)
- UE_id 2 is for rnti 2     (RA RNTI as of today's code/config)
- we start enb by displaying UE_id 3
- there was a bug: we need to lock when resetting UE ids (reset_ue_ids)

added LUT for finer-grain ULSCH power measurement compensation based on TBS. Still seems too high, to be checked some more.

see commit 622b919b

TODO: if the UE did random access (followed by a MAC uplink with
CRNTI) because none of its scheduling request was granted, then
according to 36.321 5.4.4 the UE's MAC will notify RRC to release
PUCCH/SRS. According to 36.331 5.3.13 the UE will then apply
default configuration for CQI reporting and scheduling requests,
which basically means that the CQI requests won't work anymore and
that the UE won't do any scheduling request anymore as long as the
eNB doesn't reconfigure the UE.
We have to take care of this. As the code is, nothing is done and
the UE state in the eNB is wrong.

removed "short_offset" code from normal_prefix_mod. removed static declaration in PHY_ofdm_mod which was a cause for problems when parallelizing FFTs for FEP TX.

- change target values
- change upper/lower limit to trigger a tpc
- don't use ul_cqi from SR

The value of ul_cqi is not convincing, for both PUSCH and PUCCH,
more work/analysis is required.

put pucch metric into uci->stat before calling harq_indication. Fixes an issue with PUCCH1 SNR measurements coming from HARQ.

added deactivation of ULSCH harq process after 3rd retransmission. Avoids problem of accumulating failed RA processes.

Adjustment for received power calculation in eNB pusch procedures. Added factor to account for mcs (mimic the power control adjustment in UE).
activated periodic trace for PHR/PUSCH SNR/PUCCH SNR in MAC.