[evlatests] Autophasing

[Barry Clark]

I have made substantial changes to autophasing, to be generally
available at the next Executor deployment.

I have implemented autophasing using delays only.  This permits you
to autophase all four basebands.

The previous algorithm for autophasing, setting delays and then
using the L302 phase capabilities to phase the array, has been
preserved;  the script call for phasing in this mode is
     autoph = subarray.registerPhasing(<baseband-subband>, 
Phasing.DELAYANDPHASE)
     subarray.usePhasing(autoph, <baseband>)

I like the way the delay only algorithm works well enough that I
have made it the default, though I have doubts about using it at
L band, where it can cause a substantial phase slope across the
phased subband.

I have also enabled a capability for having the script turn off the
delay determination, in mode DELAYANDPHASE, and thereafter adjust only
phases.  The call is
     subarray.setPhasingType(autoph, Phasing.PHASE)
The timing of the effectuation of this can be confusing.  Because it
is looked at at the time that new data arrive from Telcal, it will
take effect two scans before where it appears in the script.