[evlatests] delays with widar

[Ken Sowinski]

IF based delays (the DIGITIZER* terms) have been set for using
the delays measured at Widar.  The largest delay error at the
moment is 2 ns and most are less than 1 ns.  This is now close
enough to zero that we should be able to easily tell when there
is a change of delay.  Antennas/IFs which are not working today
may still have large residual delay errors.

Delays can be monitored on the fringe display for any scan which
has ScanIntent set to CALIBRATE_xxxxx regardless of xxxxx.

As expected delays at bands other than X band are all small as
they have already been registered with respect to X band using
the old correlator and any band differences arise in the antenna.
Delays have now been measured at L, C, S and X bands.  The high
frequency bands are next.