Disable handshake delay for users that are exempt from blacklist checking.

The handshake delay exists so results from DNSBL's can be checked before
the user is fully online. Whenever someone is exempt from DNSBL checking
it serves no purpose, so we mark it that the user has no handshake delay.
This will speed up connecting by up to 2 seconds (by default).
Also updated WebIRC example to suggest this now:
https://www.unrealircd.org/docs/WebIRC_block#UnrealIRCd-side

src/modules/blacklist.c

@@ -558,9 +558,15 @@ int blacklist_start_check(Client *client)
 {
 	Blacklist *bl;
 
-	/* If the user is on 'except blacklist' then don't bother checking... */
 	if (find_tkl_exception(TKL_BLACKLIST, client))
+	{
+		/* If the user is exempt from DNSBL checking then:
+		 * 1) Don't bother checking DNSBL's
+		 * 2) Disable handshake delay for this user, since it serves no purpose.
+		 */
+		SetNoHandshakeDelay(client);
 		return 0;
+	}
 	
 	if (!BLUSER(client))
 	{