Basically, build_helper has been adapted so that:
  ./buil_oai -I -w USRP
works for Ubuntu 17.04 and 17.10.

Concerning those systems:
- compilation with "--eNB --UE -w USRP" works
- the enb softmodem runs on 17.04 (not tested on 17.10)
- nothing else has been tested.

Users should report any problem.

Summary of changes:
- bug fixes: random access, crash on physicalConfigDedicated)
- some work on the UE to have it functional again
- IQ record and playback (work from Nokia)
  see documentation at: https://gitlab.eurecom.fr/oai/openairinterface5g/merge_requests/244

Conflicts:
	targets/DOCS/oai_L1_L2_procedures.pdf

Merge branch 'fix_ue' of https://gitlab.eurecom.fr/florian.kaltenberger/openairinterface5g into fix_ue

making oaisim_nos1 compile

physicalConfigDedicated may be legitimately NULL at some places
with the current code.

A cleaner solution is needed (we should always have a dedicated
config, initialized with values from the 3GPP specs, not have
a NULL as we do now).

Even if the old UE is not found, we have to cancel the random access.

Merge branch 'fix_ue' of https://gitlab.eurecom.fr/florian.kaltenberger/openairinterface5g into fix_ue

Conflicts:
	targets/DOCS/oai_L1_L2_procedures.pdf

Summary of changes:

- minor changes in RA code (functionality not changed, only notation)
- automatic indentation of some files (with indent -kr)
- bugfixes for TDD in RRU (IF4p5) and timing statistics of fronthaul and
  compression

changing of notation for Random-Access procedure to match documentation. Function remains the same. Indentation (-kr) run on all files in LAYER2/MAC

Summary of changes:
- fix a bug with Timing Advance.
  This should improve the stability of the connection
  (for now, only the scenario with one connected UE works).
- use RRC Release 14.3
- add some T tracers, minor fixes for T

Conflicts:
	common/utils/T/.gitignore
	common/utils/T/tracer/Makefile

Sometimes when the user does ctrl+c to quit, it may not quit
if nothing comes on the socket. Closing the socket in the
signal handler fixes this.

Do not link the X stuff for tracers not needing it.

Later on, use this file with gtkwave.
To be used to check realtime behaviour of the system.