Fixed a stack overflow bug when closing the gui

Added some stuff in advance for 1.17 support

Updated internal API usage

Code cleanup for future maintenance

Added back Paper API for compatibility with some events (Plugin is still fully functional with Spigot)

Fixed hat being removed when launching a projectile

When models are updated, only the ones required are updated

Fixed a bug where the armor stand for backpacks was deleted and threw a bunch of errors

Refit models on player respawn

Added the option to no longer use async when updating models (Not recommended) [Use if your having some weird issues to see if it fixes]

Fixed a bug where the latest resource pack would not be downloaded because the pack hash was not correct

Added a few new backpacks to the default pack that people can try out!

Added the "/cosmo reload" [Permission: "cosmo.command.reload"] command to update packs on the fly without full server reloads/reboots. >> HOWEVER << it is still highly recommended to restart when updating packs to avoid anything breaking.

Added a temp/perm fix to a weird bug where something was throwing null even though nothing was null :/

Cleaned the backend for future easy maintenance and features

Removed code which was being run that didn't need to be run and was doing nothing :/