Merge in CASA/casa6 from CAS-14176 to master
* commit '1437e4150a1541809b15826462d9916a6a289dca':
add a longer description [CAS-14176]
FITS header values are limited to 68 characters [CAS-14176]
ORIGIN header entry varies [CAS-14176]
add function to header comment [CAS-14176]
move image::fitsheader member function test from stand-alone to large test file [CAS-14176]
add test for image::fitsheader member function [CAS-14176]
add image tool member function to return a FITS header as a dict [CAS-14176]