Add step console command to advance n ticks

Cherry-picked from https://github.com/citymania-org/cmclient
Commit: 5ce2d21223a96934a83b8da43434c7a81f001ef0

src/misc.cpp

@@ -83,6 +83,7 @@ void InitializeGame(uint size_x, uint size_y, bool reset_date, bool reset_settin
 	ClearDesyncMsgLog();
 
 	_pause_mode = PM_UNPAUSED;
+	_pause_countdown = 0;
 	_game_speed = 100;
 	_tick_counter = 0;
 	_tick_skip_counter = 0;