Add failure messages to savestates loading/saving. It's misleading to always say "Loaded state" or "Saved state", even if it fails. Plus, result was unused up to this point.
Clean up slightly.
Restructure load/save failure message by reverting it back to the original and add a translation ini key instead. Much simpler, and cleaner.
Fix a comment and remove an old comment.
Make failure reasons translatable.
Simplify error message via better translation key/message.
Make keys look more natural in case we have an untranslated key, and give a generic error for the missing version/not found keys.
Merge pull request #2432 from thedax/saveStateFailReasons

Add failure reasons to savestate OSMs.