support python 3

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@21770 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
6443: try to use remove unused objects tool


git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@21771 4ae1f11a-8b86-4847-b8af-ab372f36d1fd