Perform the routing of a pair of request and response objects.
If the request method is VSGI.Request.TRACE, a representation of the request will be produced in the response.
If nothing matches, the one of the following error will be thrown at the bottom of the routing:
* a Valum.ClientError.METHOD_NOT_ALLOWED if alternate methods exist * a Valum.ClientError.NOT_FOUND otherwise
If the request method is VSGI.Request.OPTIONS, a success message will be produced with the 'Allow' header set accordingly. No error will be thrown.