Add ability to inject RouteCollector into simpleDispatcher

[msheakoski]

I extended RouteCollector to do some pre-processing on the route definitions before adding them and when trying to use simpleDispatcher, I discovered that I needed to duplicate that code because FastRoute\RouteCollector is a hard-wired dependency.

What do you think about adding "routeCollector" => "FastRoute\\RouteCollector" to the $options array in simpleDispatcher? It would be a backwards compatible change but add the ability to inject a custom RouteCollector.

[nikic]

Done :)

[msheakoski]

Thank you! 🌟