compiling for unb2

commit, a copy of the stratixiv variant.

-Added comments.

Added --seq vis_packet to verify correlator output packet header and payload data using a data buffer.

Added check on input range of --beamlets and --channels. Added self test on payload value being non-zero for the active TP pairs.

Use unb_apertif.py to determine active TP and visibilities and to get Apertif correlator packet info.

The test case no runs PASSED for --tel a --unb 0,1 --beamlets 0 --channels 0. It is important that dp_xonoff is on from the start.

-Added proc_common_stop_simulation() and proc_common_timeout_failure() to
 tb_tb_tech_eth_10g.
 . Reason: this tb would make the unb1 regression test hang.