introducing light element for 3D visualization, refs #36

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@16078 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
adapting expected error messages, refs #21, #1215

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@16079 29f149b2-0c63-11e1-8f5c-a347f6a9acd0