Merge pull request #512 in CASA/casa6 from CAS-10234 to master
* commit 'c02a8765eeac0760bfc8939e0367919ece37974a': CAS-10234 more comprehensible variable name CAS-10234 rename image to image_data CAS-10234 import numpy as np CAS-10234 remove unused variable CAS-10234 move the code unrelated to plotting outside try-block CAS-10234 make sure plotter is always closed CAS-10234 remove if block for CASA 5 support CAS-10234 replace pylab with pyplot CAS-10234 run all tests on macOS (not skip)
