Merge pull request #211 in CASA/casa6 from CAS-13079 to master
* commit 'cf3d70dd35772386585b8e2c0c68201df4cd1b57':
add test to verify mode='spix' fix
make casa 5/6 test_immath.py the same file
fix CASA 6 bugs, remove global variables, update variable names CAS-13079 spix bug fix and make CASA 5/6 task_immath.py same file