PC5-U - passing (source,destination) down to PDCP/RLC/MAC (first alternative - mapping of L2Ids form IP Addresses

Seemed to have fixed pnf(UE) -vnf(eNB) sync issue. Works up to the reception of RRConnectionReconfigurationComplete message at the eNB but crashing after that.

Works up to the reception of HI_DCI0.request at the UE-PNF. Sometimes Msg3 arrives later than expected at the eNB-VNF.

Conflicts:
	targets/RT/USER/lte-ue.c

Works up to the reception of the RA_RESPONSE at the UE. Crashing at fill_rx_indication_UE_MAC just before sending Msg3.

Fixed the issue with synchronization but only for the case o running both eNB (vnf) and UE (pnf) processes in the same machine. Receiving and decoding now all MIBs and SIBs1/2/3.

Merge with Thin's last commit

Testing works up to the reception of SIB1/2/3 from the UE through nfapi, but there is an issue with missing some of the nfapi messages for some frames.