added avx2 optimized turbo decoder for 16-bit LLR.  This decoder parallelizes by decoding 2 code segments concurrently. requires updates dlsch_decoding.c to identify when new parallel version can be used. other minor changes related to memory allocations for future avx2 optimizations (32-byte alignment).

conversion of some sse4 code to avx2 for turbo encoder.  No noticeable improvement (output expansion for encoder doesn't benefit much because of unpack instruction difference on AVX2.

maxh adjustement in dlsch_demodulation (to be checked further for other mcs)

exit criterion in dlsim to allow estimation of lower BLER.

minor changes in openair_device structure (naming of fields), calibration information for X310 timing, some initializations from lte-softmodem.c for USRP moved to usrp_lib.cpp

Merge branch 'enhancement-43-AVX2' of https://gitlab.eurecom.fr/oai/openairinterface5g into enhancement-43-AVX2

Conflicts:
	openair1/PHY/LTE_TRANSPORT/proto.h

Merge branch 'feature-34-test_framework' of https://gitlab.eurecom.fr/oai/openairinterface5g into feature-34-test_framework

adding perfect_ce to mbmssim

Merge branch 'develop' of https://gitlab.eurecom.fr/oai/openairinterface5g into feature-34-test_framework

adding error checks in dlsim