JOSM/wikipedia: fix #josm8618



git-svn-id: http://svn.openstreetmap.org/applications/editors/josm/plugins@29521 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4
JOSM/wikipedia: use SwingWorker to fetch/update entries asynchronously

git-svn-id: http://svn.openstreetmap.org/applications/editors/josm/plugins@29523 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4