Add Core::UniformOperations
Core::Shader: Add utility methods contains_uniform(), get_uniform_info()
Core::ShaderFactory: Rename some methods to reflect pluraility
Add Core::update_uniform shim for textures
Framework::IRenderable: Add method update_uniforms()
Update tests
Framework::Material: revise uniform use, add method update_uniforms()
Framework::Renderable: Implement IRenderable::update_uniforms()
Framework::RenderSystem: trigger uniform updates
Update TriangleSample with a working uniform
Update shaders and material descriptions for TriangleTestJson
Fix some indentation