fix #1395. However, the solution is very specific to the test case

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@16814 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
refactoring refs #12, #775

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@16815 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
now writing roundabouts to .edg.xml refs #775

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@16818 29f149b2-0c63-11e1-8f5c-a347f6a9acd0