skin overrides

the mod has had a major rework, which should reduce lag, especially when many players are in the game!

other changes:

• new supported versions: 1.18.1 - 1.20.2!
• the library is now reloaded every 2 seconds instead of only when the screen is opened
• the player faces on the overrides screen now look nicer
• added a button for conveniently adding new overrides
• added a key to directly open the overrides screen (defaults to O)
• pressing the enter key in the library search now acts like pressing the add button