Summary of changes:
- heavy code cleanup (#ifdef removal)
- bugfixes

Merge remote-tracking branch 'origin/issue-285-connect-disconnect-multiple-time' into develop_integration_2018_w04

Conflicts:
	openair1/PHY/LTE_TRANSPORT/ulsch_decoding.c
	openair1/SCHED/defs.h
	openair2/LAYER2/PDCP_v10.1.0/pdcp.c
	openair2/RRC/LITE/rrc_eNB.c

As reported by Emad Alizade:

    According to "Issue255 256 257 paging reesta release" that has been
    merged in develop version, we have a question: In rrc_eNB_free_UE()
    function only all ulsch related memory of user has been cleaned, but
    I think not only ulsch memory but also dlsch memory must be cleaned.
    I tested the latest develop version and with repetition UE attach-detach
    procedures we find that the dlsch memory has not been cleaned and after
    repeat this sequence (45 times) assertion with cause UE_id!=-1 (no free
    or exiting dlsch_context, dci_tools.c: fill_dci_and_dlsch() ) occurred
    and no UE will be attached to system.

The fixes in this commit are from Emad Alizade.

Summary of changes:
- Implementation of paging (see issue #255 in gitlab)
- Implementation of RRC RE-ESTABLISHMENT (see issue #256 in gitlab)
- Implementation of RRC CONNECTION RELEASE (see issue #257 in gitlab)

Some modifications with timers have been done.
Expect (and report) problems, thanks.

What has been tested:
- monolithic eNB 5 and 10MHz with one commercial UE. UDP and TCP
  traffic, uplink and downlink, with iperf (with a third party
  EPC, not openair-cn). TCP downlink traffic is not stable.
  Reason yet unknown. Will be fixed later.

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

Fix #582, RTAI, RTAI_ENABLED, ENABLE_RTAI_CLOCK, RTAI_ISNT_POSIX, _RTAI_MATH_H, CELLULAR, TIMER_ONESHOT_MODE, EMOS, EMOS_CHANNEL, OAI_EMU, OPENAIR_EMU, PHY_ABSTRACTION, PHY_ABSTRACTION_UL removed

Summary of changes:
- integration of Cisco work on nFAPI.
  See commits 7757b9e7
  and 922b5b59 for details.
- support Ubuntu 17.04 and 17.10
- bugfix: DCI padding bits
  This bug made the system non-working because the DCIs for
  SIBs were wrong. See commit c5ca2bd8
  for details.
- fix issue 281: IQ record/playback explicit filename segv.

Merge remote-tracking branch 'origin/hotfix-dci-clear-padding-bits' into develop_integration_2018_w02

This commit fixes issues introduced by the previous commit.

Summary of work:
- cleanup:
  - fix LOG_XX to be less verbose
  - fix cmake_targets/CMakeLists.txt
  - fix oaienv
  - remove dead code
- bug fixes:
  - in openair1/SCHED/fapi_l1.c we had:
      eNB->pdcch_vars[subframe&1].num_dci           = number_dci;
    should be:
      eNB->pdcch_vars[subframe&1].num_dci           = 0;
    This bug let the PHY send more DCIs than what should have been
    sent because num_dci is incremented later on in the code.
    This fix may be a problem for fapi mode, to be checked.
  - add new T VCD traces
  - revert openair1/PHY/TOOLS/file_output.c to 'develop' version
  - remove thread_id in logRecord/logRecord_mt
  - revert (and adapt) configuration files
  - be careful when doing frame++, we need to % 1024
  - revert target_rx_power in openair2/LAYER2/MAC/eNB_scheduler_ulsch.c
- NFAPI:
  - the open-nFAPI code has been included in the repository. See nfapi/README.
    Maybe we should "git clone" the Cisco repository instead. We have to be
    careful of availability though.

What has been tested:
- monolithic eNB FDD 5/10MHz with one UE, iperf UDP/TCP uplink/downlink

Anything else may fail to work, especially the FAPI mode, which has not
been tested at all.

It has been chosen to not include the full history of commits
from David. He included a binary version of wireshark, probably
a modified one that understands NFAPI. Wireshark is released under
the GPL license, we cannot include it in the repository. We could
have done a next commit to remove this binary. But then it would
still be present in the history of commits, which may not be allowed.
And it would take space on disk. We could edit the history to remove
wireshark entirely. But this operation is too complicated.

There was also a pcap capture file, which has nothing to do in
the history of commits and would take space on disk. There again,
it's too difficult to edit the history to remove it.

There was a file .gitignore that was also removed.

The original history can be found on David's repository:
https://gitlab.eurecom.fr/daveprice/openairinterface5g/
The branch is: nfapi-ru-rau-split.

A copy of that branch has been included in the internal OAI
repository, for those who have access to it.
The branch is the same. The last commit ID is
9106438239e0bc626ff1fa1d97d911caadd0fbb9.

You can compare the current commit with the commit 9106...
to see what differs.

The current commit has to be considered non-working.
The commit following the current commit will fix problems with
the work in the current commit.

If you use git bisect, don't spend time analyzing the current
commit.

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.

The problem is the following (as reported by an user):

  "one UE is attached to OAI system. UE is near the antenna. Try to detach
  the UE and attach again. Repeat this procedure for 5-6 times. OAI system
  does not work and any the UE can not attach to this system. I use TEMS
  software and I can see MIB signaling on this UE but UE can not decode SIB1
  and SIB2."

What happens is that the DCI for SIB1 and SIB2 is not cleared before
use. That is the bits in the 'padding' field keep the values that were
set before. If the structure has been used to transmit other DCIs
(eg. for UEs) in the past, it may be reused with some of those bits set
to 1. When receiving this DCI, the UE won't accept it because it
gets some bits at 1 where it expects them to be 0.

The short-term/quick solution is to clear the 'padding' field.
A better solution would be to rewrite this part of the code,
which is way too complicated for what it does. But this takes
too much time.

In dci.h the field 'dummy' of some structures was renamed to 'padding'.
The fields 'padding32' and 'padding64' were also renamed to 'padding'
for consistency.

Some structures (DCI2B_1_5MHz_TDD, DCI2B_10MHz_FDD, DCI2D_1_5MHz_FDD,
DCI2D_5MHz_FDD, DCI2D_10MHz_FDD) had a 'padding' field at the end, which
was renamed to 'padding0'. I don't know if this field should be here at all.
To me this field looks very suspicious. When we test DCIs 2B and 2D we
should be careful.