By default, eNB are now frame/subframe synchronized in time (that is they
all transmit the exact same frame and subframe at the same time).
Use -no-sync to disable synchronization.

Some bugs were fixed:
- memory initialized to 0
- ignore SIGPIPE that was delivered sometimes when an eNB disconnects
- set tx_sample_advance to 40, which is used in the usrp lib of openair
  (srsUE did not connect well with 0)