add IRCServer.clear_send_buffer() to clear queued lines

modules/signals.py

@@ -19,6 +19,7 @@ class Module(ModuleManager.BaseModule):
         self.events.on("signal.interrupt").call(signum=signum)
 
         for server in self.bot.servers.values():
+            server.socket.clear_send_buffer()
             line = server.send_quit("Shutting down")
             server.send_enabled = False
             line.on_send(self._make_hook(server))

src/IRCSocket.py

@@ -148,6 +148,9 @@ class Socket(IRCObject.Object):
 
         return sent_lines
 
+    def clear_send_buffer(self):
+        self._queued_lines.clear()
+
     def waiting_send(self) -> bool:
         return bool(len(self._write_buffer)) or bool(len(self._queued_lines))