Merge the mlg-20000518 branch onto the mainline. Change summary:

dns_dispatch_create() no longer exists.  dns_dispatch_createtcp()
	and dns_dispatch_getudp() are the replacements.  _createtcp() takes
	a bound, connected TCP socket, while _getudp() will search for
	a sharable UDP socket, and if found, attach to it and return a
	pointer to it.  If one is not found, it will create a udp socket,
	bind it to a supplied local address, and create a new dispatcher
	around it.

	dns_dispatch_remove{request,response}() no longer take the dispatch
	as an argument.

	query-source can now be set per view.

	The dispatch manager holds onto three memory pools, one for
	allocating dispatchers from, one for events, and one for
	requests/replies.  The free list on these pools is hard-coded,
	but set to 1024.  This keeps us from having to dig into the
	isc_mem_t the pools draw from as often.

	dns_resolver_create() and dns_view_createresolver() require that
	valid dispatchers be passed in; dispatchers are no longer created
	for the caller.

lib/dns/view.c

@@ -450,6 +450,7 @@ dns_view_createresolver(dns_view_t *view,
 	view->attributes &= ~DNS_VIEWATTR_ADBSHUTDOWN;
 
 	result = dns_requestmgr_create(view->mctx, timermgr, socketmgr,
+				       dns_resolver_taskmgr(view->resolver),
 				       dns_resolver_dispatchmgr(view->resolver),
 				       dns_resolver_dispatchv4(view->resolver),
 				       dns_resolver_dispatchv6(view->resolver),