update to lib-gwt-svg and lib-gwt-file for gwt-2.6.0

gwt-2.6.0 has finally been released, which is very good news. I am releasing new versions of all my GWT-based libraries and applications to provide compatibility with this new release. The whole software stack actually receives a big overhaul, and now uses JDK1.7u51 and the just released maven-gwt-plugin-2.6.0 for building.