fixing closest offset computation, refs #1352

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@17337 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
adding python unittests to nightly build, refs #82

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@17338 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
adapting to new offset calculation, refs #21

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@17339 29f149b2-0c63-11e1-8f5c-a347f6a9acd0