Route bindings stored whilst being parsed

This allows the developer to access already parsed bound variables to ensure correct loading of resources.

Currently it's not possible to construct urls in the form of /foo/{foo}/bar/{bar} where {bar} is specific to {foo}, e.g.
/person/jon/child/tim would load the same child as /person/bill/child/tim

With this update, when resolving the 'child' variable, we can test what was discovered for the parent, and load the appropriate child, ala
Child::where('name', $name)->where('parent', $route->getParameter('parent')->name)

Currently attempting to do so leads to an infinite recursion loop