version 0.12.3 released

Dear friends and users,
a shiny new SUMO release is coming your way.
The main achievements of this release are
dfrouter and duarouter improvements.

For details see
http://sourceforge.net/apps/trac/sumo/query?status=closed&group=resolution&milestone=0.12.3
and http://sourceforge.net/apps/mediawiki/sumo/index.php?title=ChangeLog

Have fun,
Daniel, Jakob, Laura, and Michael