neoSubstrate is MallardLuna's fork of Substrate, and is the library that powers NBTLoupe.
You can find more information about it in the original README.txt file, now named README-Original.txt.
You can look at the commit history to see the changes I've done. It's unlikely I'll document them much at the moment, as functionality-wise it should be identical to the original.
neoSubstrate is derived from Substrate, orginally developed by Justin Aquadro and licensed under the MIT license.
You'll find the full attribution in the NOTICE.md file. And all licenses are in the LICENSES/ subdirectory.