Begin working on the Character Persistence system

[Crystalwarrior]

Right now, Clients are everything in the underlying system, and they're strictly attached to their character reference. Characters are not separate.

However, this has introduced a number of complications when trying to separate a player from the character, resulting in inability to create "persistent characters" who continue to exist regardless of the player controlling them. This also makes it difficult to create and control various NPCs in the game world.

This pull request aims to resolve these issues by:

• Splitting up Client and Character into separate objects
• Delegating multiple Character-specific variables to said Character, while letting the Client object continue to exist strictly as a representation of a human Player
• Saving and Loading Character data, including the character's location
• Creating a hub preference that decides if character objects should continue to exist after the Client disconnects/changes character or not

[OmniTroid]

Worth mentioning that the proper spelling is 'persistence'