[Suggestion] Add an autosave file

[Hamsda]

I just had a BSoD, but same goes for power outages or similar, and lost all my progress.
It is really hard to recover from something like this, since you almost have to recheck all entrances, because nobody will remember every single cave and house they found.
I think just having the tracker autosave every so often (like 30s or so?) would counteract this almost entirely.
The autosave should probably be independent of regular saves. Not sure how to handle multiple instances of the program being run.