* Refactor window creation and size handling
* Require pixel aspect ratio to be > 0
* Fix screen scaling when window is resized
- Ensure the screen retains its correct pixel aspect ratio
- Updated public API on `RenderPass` ... this will continue to be unstable until the initial release
- Add build instructions for the internal shaders
- The example app generates a scaled version of pixel Ferris as a test.
- TODO:
- Pixel aspect ratio is still unsupported
- The `RenderPass` trait is incomplete
