flagging known bug, refs #1373, #21

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@16716 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
checking for free sockets as utility function, refs #12, #21

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@16717 29f149b2-0c63-11e1-8f5c-a347f6a9acd0