More discrete API for generating route objects.

[dantleech]

Currently you need to instantiate a UriContextCollection in order to generate the auto routes.

$collection = new UriContextCollection($document);
$autoRouteManager->buildUriContextColleciton($collection);

foreach ($collection as $routeDocument) { 
   // ...
}

This is not a very clear interface, and I think we should encourage the explicit generation of auto routes in some situations rather than relying on Subscribers.

I propose to change the API to

$collection = $autoRouteManager->generate($document);

foreach ($collection as $routeDocument) { 
   // ...
}