v5.2.3

• rename almost all occurrences of map_id to beatmap_id. I've tried to leave aliases in all occurrences so old code won't break, but if I've missed one, please update to using beatmap_id instead
• remove Cacher class, all its logic now lives inside Loader
• Circleguard's loader argument must now be an instance of a Loader class (or subclass) instead of the class itself. This is a breaking change, but since I don't think a single person is using this feature besides us, I'm making it anyway (and if you are using it, please message me because I'm very curious what your use case is!)
• add __str__ to MapUser and User