Version 4.0 - beta 5

As well as bug fixes, beta 5 includes two major components:

• SpriteGPULayer game object. This advanced renderer is designed to handle millions of background objects.
• Texture coordinates now match WebGL standards. This should bring greater compatibility with other technologies. Note that compressed textures must be re-compressed to work with this system: ensure that the Y axis starts at the bottom and increases upwards.

Fixes and Improvements

• Limit roundPixels to only operate when objects are axis-aligned and unscaled. This prevents flicker on transforming objects.
• Fix TextureSource.resolution being ignored in WebGL.
  • This fixes an issue where increasing text resolution increased text size.
• Fix DynamicTexture using a camera without the required methods.
• Remove WebGLAttribLocationWrapper as it is unused.
• Remove WebGLRenderer.textureIndexes as glTextureUnits.unitIndices now fills this role.
• Remove dead code and unused/unconnected properties from WebGLRenderer.
• Switch texture orientation to match WebGL standards.
• Add SpriteGPULayer game object.