This moves the application of the stencil reference from the DepthStencilState to Command::SetStencilReference
* First API design (many features missing, including input attachments) * Metal implementation (no OpenGL yet) * Render-to-texture demo (a little broken until we have depth buffers) * Update examples to use render passes
More like squashed history, contributors were: - Kai Ninomiya - Corentin Wallez