Move simulator to its own repository

[kanerogers]

No description provided.

[kanerogers]

I went with a monorepo to begin with, mostly because I'm lazy, rather than any focussed direction. I know bevy for instance is also a monorepo, but I'm not sure if that's the right way to go.

@Ralith @wbrickner what are your views on repository structures?

[Ralith]

Highly recommend using a single repository containing a cargo workspace for closely related projects, i.e. those which tend to have interdependent changes.

[kanerogers]

Sold! Closing this issue then.