Merge in CASA/casa6 from CAS-13003 to master
* commit 'f3a65179ef2d232f914d442da59e1b16cf67a3d0':
CAS-13003: Adjust tolerance in EOP correction tests
CAS-13003: Add more tests
CAS-13003: Fix error message
CAS-13003: Improve handling if missing EOP data
CAS-13003: Implement 'eop' mode in gencal task