Proposal: add :host keyword to create-server.

Hello, Currently create-server binds to *loopback-interface* which happens to be "127.0.0.1". BTW: *loopback-interface* is not exported, maybe it should? For remote access binding to the loopback is not really helpful. What about adding a :host keyword to create-server to expose the address we want the server to bind to? I added a patch for your review. The patch is against the latest slime versions available from quicklisp. -Frank