Pull request #780: For CAS-14288, cherry-pick tec_maps.py and related commits from CAS-14219, for CASA 6.6.1
Merge in CASA/casa6 from CAS-14288 to release/6.6.1
* commit 'c95a475e80efa62058c6e3833310a90fc441af85':
For CAS-14288, cherry-pick tec_maps.py and related commits from CAS-14219, for CASA 6.6.1