Chat messages are now displayed in chat bubbles above players heads

See merge request !27

Icon updates

See merge request !26

Fixing regression which caused uncleaned messages (i.e. with behaviors) to be broadcast to players. This is fixed by adding only the cleaned message, and then updating the previousMessage history with the original/uncleaned message.

Changed UV coordinates slightly for bottom right of the icon, to not overlap the front of the skin's hand. Updating ICONS.md assets to use new UV coordinates.

New command `/creaturechat chatbubbles set <on | off>` to show or hide player chat messages in bubbles

Seperated Player and Entity message broadcasts (different packets for simplicity). Removed extra message broadcast (which was unnecessary).

Icon tutorial

See merge request !25

Scaling all icon/skin images to 256 for clarity on tutorial, and linking to templates for downloading.

Custom Player Icons

See merge request !24

Refactor of client mixin for PlayerSkinTexture, moving to a static class, and conditional mixins for different Minecraft versions.

Removing import net.minecraft.client.util.SkinTextures (fails on 1.20, 1.20.1), adding 2 mixins for different Minecraft version support.

New Custom Player Icon support (if black/white pixel set at 31, 49), uses certain empty UV coordinates in player skin file.

Improved LLM unit tests for UNFLEE (trying to prevent failures for brave archer)

See merge request !23