[evlatests] focus

[Ken Sowinski]

I used time this morning to exercise the focus finding
machinery.  It still needs a bit of tuning, but worked
well enough for a spot check of all antennas and bands.

Antenna 26 was not available and L band was not examined.
The worst offenders were 24 at K band and 13 at Q band
each of which was off by about half a wavelength. enough
to be well worth correcting.  The measurements were all
made within five degrees of an elevation of 50 degrees.