API Changes:
- Added AdvancementManager#setHiddenBoolean(boolean hiddenBoolean) and AdvancementManager#getHiddenBoolean(): When set to true, hidden advancements that have not been granted yet will have a line drawn to them when they are in visible range despite not being visible. Can be used to create empty advancement tabs where there are no advancements visible when the tab's only advancement is a hidden root advancement. Defaults to false
- Added AdvancementManager#setCriterionPrefix(String criterionPrefix) and AdvacementManager#getCriterionPrefix(): Prefix infront of criterion names, Setting it to an empty string reduces save file size and packet size. Should be set before adding advancements or loading progress. Defaults to " criterion.". CHANGING THIS SETTING WILL RESET EVERYBODYS PROGRESS IN THE CURRENT MANAGER IF YOU DO THIS FOR THE FIRST TIME.
- Added AdvancementManager#setCriterionNamespace(String criterionNamespace), AdvancementManager#setCriterionKey(String criterionKey) and respective getters: The combination of these strings is used as a Namespaced Key that is used in packets sent to the client. Setting it to an empty string reduces packet size. Only works when criteria for advancements have not been generated yet (Use this method before adding advancements). Default to " minecraft" and " impossible"
- Added Advancement#setSaveMethod(SaveMethod saveMethod) and Advancement#getSaveMethod(): When you don't work with expert features, using the NUMBER Save Method will significantly shrink your save file sizes (only if your advancement requires 2 or more criteria). You can always switch from the DEFAULT to the NUMBER Save Method and your data will be converted automatically. If you want to switch the other way round, you have to load data while it is set to NUMBER and save data while it is set to DEFAULT to prevent save file corruption. Defaults to DEFAULT

Bug Fixes:
- Fixed a bug that caused progress to never unload when unloading progress
- Fixed a bug that caused progress not being saved for offline players when they have not been online since their progress was loaded
- Fixed a bug that caused progress not being saved when players have never been added to the manager in the first place
- Minor bug fixes