Saving and loading a saved and loaded game breaks some engine properties.

[DDR0]

1. Some properties which are marked as unserializable get serialized.

• This happens primarily to our water and acid controllers, such as those on to-nenes-house.cfg.
• See https://cdn.discordapp.com/attachments/271875323417591818/777536608403718144/save.cfg for a save exhibiting this issue. Note that it's not an unserializable variant, but an unserializable loading.
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• I've had a look at the loaded objects before and after load, but they're functionally identical as far as FFL is concerned. There's no reason I can determine that they would not save fine when they already have.

2. Some objects which are marked as hidden_in_game: true are no longer hidden in game. This seems to happen primarily with the water controllers.

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