Add family filter to match twins

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@21133 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
6338: NotImplementedError on Export a View to a spreadsheet from the People Category


git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@21135 4ae1f11a-8b86-4847-b8af-ab372f36d1fd