Fix returning true from event handlers not doing anything

Returning true is meant to consume the event, thereby preventing remaining event handlers and the rest of the game from handling it, but the check that implements this was accidentally removed in 87b81ceb45, oops.

src/lua/LuaScriptInterface.cpp

@@ -414,7 +414,7 @@ bool CommandInterface::HandleEvent(const GameControllerEvent &event)
 	auto end = list.end();
 	lsi->currentEventHandlerIts.push_back(&it);
 	bool cont = true;
-	while (it != end)
+	while (it != end && cont)
 	{
 		it->Push(L);
 		++it;