Merge in CASA/casa6 from CAS-750 to master
* commit '15e9c015c8e2516bf7341fd77a4ed303eb4c9cfd':
vector<long> -> Vector<int> fix
bug fix, trc coord can be equal to corresponding blc coord
improved error handling, refactor, more tests for getcellslice
better error handling, more tests
initlal tests for getcellslice
fixes to getcellslice
reformat