Properties toggle dialog: allow to select and copy/delete multiple keys/values, see #7846
fix #6917, fix #7895 - select multiple "member of" (fixed one non-working action in previous revision)


git-svn-id: http://josm.openstreetmap.de/svn/trunk@5800 0c6e7542-c601-0410-84e7-c038aed88b3b