port/port-discovery: How to find (and possibly make) a suitable port.
* There is some clever magic here, along with an nq-clim private extension interface (not part of the specification) for creating new port instances. For the most part, however, this is... * Actually, it's two different things, which is not right. This file both manages the *ALL-PORTS* list for MAP-OVER-PORTS, it also covers FIND-PORT and *DEFAULT-SERVER-PATH*. In order for this to work, CREATE-PORT would need an :AROUND method to update *ALL-PORTS*, removing that responsibility from FIND-PORT. * FIND-PORT requires MAP-OVER-PORTS. MAP-OVER-PORTS uses *ALL-PORTS*, and maintaining *ALL-PORTS* would require methods on both DESTROY-PORT and CREATE-PORT, necessitating three files in place of one. We might go there at some point, but not now.