Please expose functionality to allow non-Express http servers (eg. Koa) to add their own routes for colyseus-monitor

[rnd256]

I would love to use this, but it looks like an express server is required.

[endel]

It would be nice to support it out of the box, but I'm not sure how to handle this, since koa lacks a built-in router. (https://github.com/koajs/koa/blob/master/docs/koa-vs-express.md#koa-routing-third-party-libraries-support)

Supporting both koa-router and koa-route (maybe others?) may not be the best approach. If you have any ideas please let me know!

EDIT: here's how we're handling for express: https://github.com/colyseus/colyseus-monitor/blob/master/src/index.ts#L13-L18

[seiyria]

Express is still fairly commonly used. If anything at all, I think this should be made mountable to whatever a user wants (as a breaking change). That way, flavor of the month webservers will not need to be added.

[rnd256]

I like @seiyria's idea of effectively making this mountable. So, exposing functionality that would allow developers to attach the colyseus-monitor APIs and static fileserver to whichever http server framework they want.

Allowing fixed paths to be customizable is probably more hassle than it's worth, but allowing developers to specify a prefix for all the APIs might be doable.

I'll change the title of this issue to reflect this.