The abstraction mode of oaisim does not work for the moment, it's better
to exit than to crash somewhere randomly.

                since two rx threads (even/odd) are used by OAI-UE

changed the memory allocation of txdataF and beam_weigths

Beamforming is now only done when necessary. This patch is based on one from enhancement-10-harmony.

Some of them might not be correctly handled.
I put /* TODO: XXX */ where I didn't know if
the fix was correct.

fixes for precoding (turning off if nb_antennas_tx=1), configuration files, timing advance with 3/4 sampling on 20 MHz, logging in MAC