Pull in a SHA-3 implementation.
We'll need it sooner or later, particularly because SHAKE128/SHAKE256 are incredibly handy for what they do, and having a cryptographic hash that's immune to length extension attacks simplifies some of our constructs.
I have a modified version of keccak-tiny (https://github.com/coruus/keccak-tiny) that provides more familiar semantics that I can clean up for inclusion.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information