improving xml csv conversion, refs #1191

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@16680 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
adapting tests to improved conversion, refs #21, #1191

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@16681 29f149b2-0c63-11e1-8f5c-a347f6a9acd0