Merge pull request #44 in CASA/casa6 from CAS-12834 to master
* commit '39eaf2d65af3361e5701eafe1fe4a19494bab0fb':
uncomment import of casatools, CAS-12834
sync test listcal from casa5 to casa6/casatasks, CAS-12834
add basic task test of listcal, CAS-12834
sync missing import CASA5<=>CASA6, CAS-12834
add missing casalog import, CAS-12834