SPVertex data uses assertions instead of exceptions
added '(set)textureQueue' for SPTexture

Allows control over the texture loader queue when using "loadFile:" and
"loadURL:" methods. Also allowed asynchronous loading of compressed
textures.
"initWithContentsOfImage:" now uses GLKTextureLoader
using "glMapBufferRange" extension if available
changed menu offset, so the extra samples fit better
"textureWithContentsOfURL:" now supports gzip files