update NEWS for 3.4.6

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps34@23429 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
bump to 3.4.7

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps34@23432 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
Mac: Release 3.4.6

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps34@23433 4ae1f11a-8b86-4847-b8af-ab372f36d1fd