Support resizable windows

[JD557]

Ideally one should be able to define a max/min width/height in the canvas settings, and that would allow it to be resized.

It would be up to the application to check the width and height at the beginning of every frame to render things correctly.

I think forcing the window to keep the aspect ratio can be out of scope for now. It's more important to ensure that operations like redraw() don't break in the middle of a resize.

Also, I'm not sure how this would work on JS. I think it should be possible, but maybe it's simpler to just focus on JVM and Native and then leave JS to a future version.