add instructions for running GWT in superdevmode

vtm-gdx-html/HOWTO-SuperDevMode.txt

@@ -0,0 +1,20 @@
+Using GWT SuperDevMode is the recommended way for development.
+
+For an introduction see:
+
+http://www.gwtproject.org/articles/superdevmode.html
+http://www.badlogicgames.com/wordpress/?p=3073
+
+Preparation:
+- Change build.xml <property name="gwt.location" value="/home/src/gwt-2.5.1" /> to the appropriate location.
+  Then run 'ant extract-jars'
+
+- To serve tiles and the html project from the same origin one can use this apache2 configuration:
+	ProxyPass /tiles/ http://city.informatik.uni-bremen.de/tiles/vtm/
+    ProxyPassReverse /tiles/ http://city.informatik.uni-bremen.de/tiles/vtm/
+
+- Create a link to the project by 'ln -s /path/to/vtm/vtm-gdx-html/war ~/public_html/vtm' 
+  to make it available via http://localhost/~my_user/vtm
+  
+Running:  
+- The codeserver can be executed with 'ant VTMSuperDevMode'