* Begin implementing DPI generics
* Fix multithreaded example
* Format
* Fix serde test
* hopefully fix most of the errors
* Fix dpi module errors
* More error fixings
* Format
* fix macos errors
* Another error pass
* Replace bad type signatures
* more fixins
Adds fullscreen using native web APIs to the stdweb and web-sys backends.
Due to limitations of browser APIs, requests for fullscreen can only be fulfilled during a short-lived user-triggered event. This commit does automatically handle that under the hood, but it does introduce unavoidable latency in full-screening the canvas.