Changelogs:
- Fixed NullPointerException due to CKCleaner
- Optimized NBT handler
- Added built-in MHF Skins
- CompoundTag#getValue() now throws exception if you try to call it
- Updated dependency JvmKit to v1.0.7
- Now uses JetBrains NotNull annotation
- Added some Nullable annotation to make JD comments more clear
- Added new dependency: ABIF and Kotlin-Stdlib
- Removed skin directory
- Added some methods for ItemNBTHelper, allows you to work with written books and attribute system in an easier way

Why Snapshot? Because I find it is not stable yet for public servers: some methods may not work, and residual bugs maybe not discovered yet.
CraftKit for Bungeecord side will come soon!