Caves Update

-Add runtime-generated UI (Thanks SMG for the help!)
-Add support for non-mirrored/multi-layer skins
-Add support for pre-1.8 skins
-Add support for "HD" skins up to 1024x1024
-Make menu more consistent
-Fix selecting vanilla skins
-Fix menu display for various skins
-Removed herobrine

Huge thanks to everyone who helped:

* ScanMountGoat - UI Rendering and cropping code, color correction help, overall graphics genius
* Raytwo - Arcropolis API support <3
* J4C - base model rework, UV changes
* ThatNintendoNerd - material work, model revamping
* DemonSlayerX8 - initial material work
* Kalomaze - testing, minor material edits, color correction help
* tomo - testing