Replay files from saved games are incomplete

[Itms]

This is a similar issue to #3963, but in single player.

If one starts a game, saves it, loads it, and replays the file from the second session, it will only apply the commands from after the loading to a fresh initial game state, thus creating a completely new game.

This could be fixed by saving the commands as well as the state when saving a game, then upon loading the saved commands.txt would be used as a starting point.

Reported by sphyrth on the ​forums.