Merge pull request #2 from nippur72/master

update from origin
Experimental GWT 2.7.0-SNAPSHOT support added. 
Build is still use stable 2.6.1
Merge branch 'master' of https://github.com/slavap/Dart.RayTracerDemo.git
Merge pull request #13 from slavap/master

Merge pull request #2 from nippur72/master