New FileIO, Sync, SaveLoad

[Frotty]

Migration Notice:

• MultiFileIO, PreloadIO, IOTaskExecutor : Use FileIO instead
• Network, GamecacheBuffer. SyncSimple: Directly sync strings using the new extension functions in SyncSimple
• Persistable will be replaced by Serializable in the future

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Replaces the current broken and legacy implementations of saving, loading and syncing data with new and improved ones using the newly added natives. The main goals of these new packages is to be lightweight and have intuitive, simple API.

Future enhancements would be something like a Serializable interface to de/serialize classes, perhaps using the existing OrderedStringBuffer etc.

Usage examples are at the top of each package.

[Frotty]

Alright, I will merge this with the deletions, since deprecating the packages would create unavoidable warnings in the stdlib and "updating" the old classes, e.g. Persistable isn't easily done because of how the old syncing and data management works. Most of these packages don't work or only partially work anyway and I don't want people get confused by the similar package names. The plan is to replace Persistable with a new, lightweight Serializable class/interface in the future.