casa5

Merge pull request #496 in CASA/casa from feature/CAS-10516 to master

* commit '9d745e1495c9fc0ed71dbc87d5a33eec9641e262':
  Fixed a typo
  Added a feature to extend cube stokes I mask to cube multi-Stokes imaging
  Fixed to handle input mask without degenerate axes for expanding masks
  Further modification for expanding Stokes I mask. Also added some unit tests.
  added expansion alog stokes for cube
  merged from cas10516 branch