Merge pull request #427 in CASA/casa6 from CAS-13252 to master
* commit 'dd159d787c3f92a25a9cb840be8db7d2744cd68a':
pick up casaviewer wheel (CAS-13252) CAS-13252 updating tclean documentation to reflect mpi interactive capabilities CAS-13252 updating build.conf to reference in-dev casaviewer CAS-13252 fix the calls to open the viewer to be macos compatible (no execvpe on mac) CAS-13252 trick MPI into not knowing that we're running casaviewer with MPI