Merge pull request #459 in CASA/casa6 from CAS-13381 to master
* commit '33b589df64a80814ebd0d684bea8c00570927b4e':
Set build.conf plotms master version
Fix caltable averaging frequencies when not channel averaging
Fix frequency values for CT channel averaging, axis labels
Disallow antenna averaging for pure antenna-based tables
Add obs id to averaged cal table for plotms
Update build.conf with latest plotms wheel
Add channels per bin to cal table channel averaging
Cal table averaging fixes in atm overlays, pol selection
Set default channel selection after channel averaging
Cal table channel selection fix
Add channel selection to non-channel averaging
