Refactor WorldSettings, CustomObjectManager

CustomObjectManager has lost some of its responsibilities. It still
holds both the global objects and the object loaders, but no longer
loads/finds objects. That is now done by the CustomObjects class, which
represents a collection of custom objects.

WorldSettings is a settings manager that can load from either the files
or from the network stream. This class should be split into two, with
both implementing the same interface. The interface has been created
(ConfigProvider), but the class hasn't been split up yet. This will
happen at a later date.

Most of the old methods/fields are still around to prevent BO3Tools from
breaking. A little bit of effort on our part makes an update for
BO3Tools unnecessary. Once we are at Minecraft 1.8 everything will break
anyway (Forge mods break any Minecraft version, and Bukkit will be
gone), we can remove all deprecated things then.