NGon fix for bug reported on Starling Forum

http://forum.starling-framework.org/topic/hittest-starlingpunk-extension-graphics
Fix for Fill texture bug reported

This problem was reported here:

https://github.com/StarlingGraphics/Starling-Extension-Graphics/issues/94
Fix for fill touch calculation not working right

THis is an odd one. I had testcases where this worked correctly, but now
they don't and .. anyway, this seems to fix the Fill geometry based
touch issue reported here:
http://forum.starling-framework.org/topic/hittest-starlingpunk-extension-graphics