[daip] zero vis

[Eric Greisen]

Lorant Sjouwerman, NRAO writes:

 > Because I'm running the (VLBA) pipeline, I am concerned about robustness.  
 > At least one task -CLIPM- can be improved in my opinion.
 > 
 > CLIPM, and maybe other tasks, cycles through the source list to do its job
 > (fitting a continuum to the source and clip on the residuals). However,
 > some observations end up with zero visibilities in the data, eg due to long
 > slews. To me, zero visibilities should mean that there is nothing to clip -
 > not croak. The only way to get CLIPM to finish now is to physically remove
 > that source from the SU list. Could you perhaps put a statement in CLIPM to
 > skip the source if there are no visibilities for a particular source?
 > Thanks anyway.
 > 

Fixed in CLIPM and UVMLN.

Eric