Updating the glutin dependency to a 0.21.0-based branch, based on the migration guide at:
https://gentz.rocks/posts/glutin-v0-21-0-migration-guide/
* Remove glutin::ContextTrait
* Create window with ContextBuilder instead of WindowedContext::new
* Add .window() accessor on WindowContext, since it now dereferences to Context
In order to not break wasm32-unknown-unknown compilation, a minor fork is used of glutin v0.21.0 and a corresponding version of winit: https://github.com/iceiix/glutin/pull/1https://github.com/iceiix/winit/pull/2
- with stubs to compile (but not run, see issue #115)