refactoring some castings and removing an inf loop, flagging guess-empty-flows as unusable, refs #1172

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@15801 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
fixing imports

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@15802 29f149b2-0c63-11e1-8f5c-a347f6a9acd0