merged from master

* remotes/origin/master:
  handling nicely the repopulation of the buffer when the drawableobject is cleaned. also cleared the constants a little bit up
removed the allocations on each frame
caching projection matrix in the camera and constant access for uniform locations in shaders
cleaning the renderer state in the GL thread safely
Merge branches 'fun-gl-2' and 'master' of https://github.com/jcxavier/fun-gl into fun-gl-2
refactored the shader a bit, added textureshader and sprite
sprites working. added setters and getters for scale in game object and updated the tests to illustrate sprite working
Merge pull request #15 from jcxavier/fun-gl-2

Sprite and Texture implementation
added a default camera if the camera to be set is null
implemented isVisible property into updateable and checking flag before drawing
updated the sample to reflect alpha and visibility changing
resolved merge conflit