BufferObject: Add additional uploadData(...) and getGLId() methods.
Add TextureType::TEXTURE_BUFFER (Experimental feature).
Use PixelFormat.getValueType() instead of .getBytesPerComponent() to identify value type.
RenderingContext: Add support for binding images (untested).
TextureUtils: Add createDataTexture(...); internal cleanups.
Texture: Allow downloading (u)int32 textures.
TextureUtils: cleanups.

- createBitmapFromLocalTexture() uses the texture's local bitmap.
- Factories return a reference instead of a pointer.
- remove duplicate code.
- Parameters that must not be null are passed by reference.
- cleanups.
Texture: improve openLocalData(...) for empty textures.
Fix integer textures.
TextureUtil: Improve pixel format conversion.
Texture: Move definition of a Texture's pixelFormat into dedicated PixelFormatGL structure.
Texture & TextureUtils: implement and use TextureUtils::glPixelFormatToPixelFormat(...).
Update file header.
Fix pixelFormatToGLPixelFormat(...).
Texture: Don't apply texture parameters for buffer textures.
Simplify TextureUnitUsage parameter.
Fix ImageBinding.