warning with invalid plugin preferences

git-svn-id: http://josm.openstreetmap.de/svn/trunk@5858 0c6e7542-c601-0410-84e7-c038aed88b3b
see #8274, #8601 : cancel now works while parsing OSM 

git-svn-id: http://josm.openstreetmap.de/svn/trunk@5859 0c6e7542-c601-0410-84e7-c038aed88b3b
fix #8604 - Internal presets: add `shop=newsagent`

git-svn-id: http://josm.openstreetmap.de/svn/trunk@5860 0c6e7542-c601-0410-84e7-c038aed88b3b
Remote control: start/stop HTTP server without restarting JOSM

git-svn-id: http://josm.openstreetmap.de/svn/trunk@5861 0c6e7542-c601-0410-84e7-c038aed88b3b