idea: use a webassembly runtime to host mode plugins

[malcolmstill]

With ulubis, one of the nice ideas (I think) was the mode system where a standard desktop-like interface is a mode, and then alt-tab window switcher behaviour is actually a completely different mode that gets pushed onto a mode stack. The modes had a common api (e.g. a render method, a handle key method etc.) that when implemented produces the desired behaviour.

I want the same for foxwhale, but what might be cool is making those modes wasm modules so that you might load them in as plugins at runtime or in such a way where you are less trustful of the source (compared to, say, a dll)