#1938980: Move controller derivation to route enhancers started off so simple. We just want to move some classes around for clarity, and to make it easier to extend. In the process, though, we realized there were still unresolved bugs in the Ajax system, and fixing THOSE is taking considerably more time and has a long dependency chain. Sigh.
In an effort to get things moving, this contains JUST the code-moving-around parts. The ajax resolution code is still what's in core now, which doesn't handle new-style routes, just old-style routes. We know that, it's OK, we'll fix it in the other issue, but let's get in the parts we can.
Patch as soon as I have a nid.
