Updated the XSLT for formatting ARB_debug output
Multiple texture-related changes

- Added the TextureTargetDimensions function.
- Added the TexImageSpec class.
- Added the Texture::Image and DSATextureEXT::Image functions.
- Added syntax-sugar operators for specifying some of the Texture's
  and DSATextureEXT's attributes.
- Updated a few examples to show the new functionality.