Pull request #1067: CAS-14454
Merge in CASA/casa6 from CAS-14454 to master
* commit '21c177edd7dc97ff82dd395da776255d46cd9553':
Fixed: trying to just fill model column was not copying over the tt images to the cube model for prediction
As per reviewer comment added a squint correction test to the mvc test.
Added unit tests and fixed a per pol normalization
Fix an oversight ...when having pol images the full pol pb was being used rather that each stokes.
CAS-14825 : Remove traps for nterms < 2 and MT-MFS
This allows nterms=1 to run, which is mathematically consistent with
using hogbom clean via different internal machinery.
We will deprecate this usage mode at a future date, but this resolves
issues with running the pipeline in this mode.
