feature: timecapsule

[tuturto]

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Create special room that has a time capsule buried in the middle. have some appropriate way of marking it (maybe have some unmarked ones too). Fill capsule with all kinds of items and documents (maybe have a theme here). Can be dug out like a grave.

[tuturto]

This can use exhuming code for graves, but with either different or parametrized events (we don't want messages about graves, but about time capsules).