Add support for DRO knocking

Author: Crystalwarrior

server/commands/areas.py

@@ -666,7 +666,12 @@ def ooc_cmd_knock(client, arg):
                     f"Failed to knock on [{area.id}] {area.name}: Current area is locked!"
                 )
 
-        area.send_command("RT", "knock")
+        for c in client.area.clients:
+            if c.software == "DRO":
+                # DRO client doesn't support custom RT packets. So for now just send a message with the knock effect (ding id 7) instead.
+                c.send_command("MS", 0, "", "","", "", "", "", 0, -1, 0, 0, 0, 0, 7, 0, "")
+            else:
+                c.send_command("RT", "knock")
         if area == client.area:
             area.broadcast_ooc(
                 f"💢 [{client.id}] {client.showname} knocks for attention. 💢"