Merge pull request #7 from aidangrabe/master

Change DisplayObjectContainer removeChildren() method to take optional parameters
api docs and a few minor bug fixes
moved docs
Update README.md
Update README.md
minor bug fixes and code clean up
Change DisplayObject generateTexture method signature to match Pixijs signature

generateTexture method now matches:
http://www.goodboydigital.com/pixijs/docs/classes/DisplayObject.html#method_generateTexture