Add very initial ChanServ and NickServ virtual clients

As well, add channel registration and re-applying founder privs on the first client joining the channel. I'm going to re-architect our modes system to better acocunt for this sort of change.

irc/nickserv.go

@@ -0,0 +1,24 @@
+// Copyright (c) 2017 Daniel Oaks <daniel@danieloaks.net>
+// released under the MIT license
+
+package irc
+
+import (
+	"strings"
+
+	"github.com/DanielOaks/girc-go/ircmsg"
+)
+
+// nsHandler handles the /NS and /NICKSERV commands
+func nsHandler(server *Server, client *Client, msg ircmsg.IrcMessage) bool {
+	server.nickservReceivePrivmsg(client, strings.Join(msg.Params, " "))
+	return false
+}
+
+func (server *Server) nickservReceiveNotice(client *Client, message string) {
+	// do nothing
+}
+
+func (server *Server) nickservReceivePrivmsg(client *Client, message string) {
+	client.Notice("NickServ is not yet implemented, sorry!")
+}