add regression test for FK5Coordinates.separation
add regression test for copy.copy and copy.deepcopy on a Time object
Implement Time.__copy__ and Time.__deepcopy__

closes #891
change __copy__ to use replicate to better act like a shallow copy
Move copy/deecopy after replicate
Merge pull request #891 from eteq/fix-fk5-deepcopy

Add Time copy/deepcopy to fix bug in FK5Coordinates.separation