Standard Graphics 11/11/19

This release completely revamps Standard Graphics. It replaces the SDL2 dependency with pure Rust. It brings full, well-documented support for event handling and more complex graphics.

The previous release was still an experimental Standard Graphics. This is the real deal. I'm quite excited to begin using it for personal work and I would be absolutely thrilled if others feel similarly.

Also, please post issues on the GitHub repository. I try to be as responsive as I can.