Doku's RPG

Added:

• pale hanging sign gui
• empty air GUI

Replaced:

• pale hanging moss
• pale log top
• pale moss carpet side
• stripped pale log

Edited:

• pale leaves
• pale oak sapling
• polished blackstone bricks
• creaking mob

Other Changes and Notes:

• removed backwards compatibility related files for 1.21.1 to 1.20.3