Merge in CASA/casa6 from CAS-8434 to master
* commit '559a429e7e65ffe4e137b0bebf66e7af6dde7971':
CAS-8434 : Edited the superuniform docs a bit.
CAS-8434 : Two weighting options did not have uvtaper listed as a sub-parameter. Added them. ( Need to test that they are actually honored, when run from inp/go as well as as a tclean command. )