refactor: improve (auto)saving system

[EdVraz]

fixes issues regarding autosaves and combines autosaves and normal saves into one function.

fixed:

• issue where the autosave value for "timer remaining" would always be 0 (-1 - (-1)) because of the wrong variable used. This renders autosaves unusable (the save is created, but not considered as the remaining time is 0).
• issue where a broken map could save as the last played map in the autosave, making the run unusable as the save file destroys when the run is loaded but the game crashes again due to the map being broken

changed:

• combined save & autosave into one function as only one variable differs.
• Autosaves now happen on every PB instead of when the map changes.

A quick new release for this would be appreciated, as currently runs are not continuable if the game crashes, see Scrapie's stream, for example.

[EdVraz]

Draft - I will try to update the autosaves to create an autosave on PB instead of map load. This makes the saves more accurate for random game crashes and prevents the chance of a broken map being saved, essentially rendering the run useless.