Cleanly remove player when an exit is requested

The client will actually do this itself when clicking the quit button in the tilde menu, but for the idle timer the connection would remain open until the game is closed.

src/PlayerManager.cpp

@@ -369,6 +369,9 @@ static void exitGame(CNSocket* sock, CNPacketData* data) {
     response.iExitCode = 1;
 
     sock->sendPacket(response, P_FE2CL_REP_PC_EXIT_SUCC);
+
+    sock->kill();
+    CNShardServer::_killConnection(sock);
 }
 
 static void revivePlayer(CNSocket* sock, CNPacketData* data) {