Implement save item corruption prevention

[SylviBlossom]

Implemented the system to attempt to prevent item corruption by saving additional information for each item, aside from just their sequential IDs. This hasn't been fully tested with LLL mod item behaviour; there's a lot involved with that which is hard to test without many mods currently implementing scrap using LLL's systems.

This saves a bunch of additional values tied to each item sequential ID and, if it finds out a saved item doesn't load with the same name as before, goes through and fixes every item ID based on a scoring system where a bunch of these saved values are matched together, and they add up to a score which certain variables are much more important to - it then replaces the item's ID with the highest scored one (or, if the score is low enough, just removes the item altogether).

There's probably bound to be some flaw in the system I haven't found yet; an option to toggle this functionality would be good, but I'm not sure how you'd prefer to set that up. If you'd like to implement that yourself, returning early in SaveManager.LoadShipGrabbableItems to cancel the process would do the trick.

There's also a few general adjustments to saves:

• New "parityStepsTaken" saves the "StepsTaken" stat which is also saved in the vanilla file and, when loading, if they aren't the same value, any loading of LLLSaveFile values will be cancelled since the LLLSaveFile may be out-of-date
• The LLLSaveFile class doesn't need a prefix since that's auto-defined, and would have prevented LLL save data from loading if the save was renamed
• "CurrentLevelName" now only saves to the file when the rest of the game saves to the file

[melvyn2]

Here's a build of this PR:
LethalLevelLoader.dll.zip
Seems to work so far, even restoring items after loading a corrupted save