[evlatests] flagging of EVLA antennas

[Ken Sowinski]

As promised this morning flagging is now enabled for EVLA antennas.
I expect this to improve rather than degrade the quality of data
when EVLA antennas are in use, but be aware that if you don't find
all the data you expect, you should  try to fill again asking fillm
to ignore online flagging.

Flagging events include antenna off source, subreflector mispositioned,
and synthesizer out of lock.  We plan to add L305 out of lock when the
hardware ten second tick detection is sufficiently robust.

What I am most worried about is how data is flagged for pointing
or raster scans.  I have tested this and it behaves as I expect,
but experience will tell if everything is really correct.

If you have any doubts about what is happening please consult
with me.