Tracer2: Change from Java 1.7 to 1.6.

git-svn-id: http://svn.openstreetmap.org/applications/editors/josm/plugins@30049 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4
Tracer2: update to [josm6340]

git-svn-id: http://svn.openstreetmap.org/applications/editors/josm/plugins@30050 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4