resolving local schemas, refs #1135

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@15583 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
adapting error message for local schema, refs #21, #1135

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@15584 29f149b2-0c63-11e1-8f5c-a347f6a9acd0