refactoring vehicle coloring and enabling more vehicle color schemes for meso-gui refs #36

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@17271 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
added more colors when coloring lanes/edges by speed refs #36

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@17272 29f149b2-0c63-11e1-8f5c-a347f6a9acd0