0.4.0

Imported new curves:

• #139 - Import ed25519 curve
• #122 - Import secp256k1 curve

Support for nonnative arithmetic in circuits:

• #120 - Imported NonNativeFieldGadget from https://github.com/arkworks-rs/nonnative and built a NonNativeGroupAffineGadget on top of that;
• #143 - Review and partial refactoring of the nonnative module;
• #164 - Optimization of nonnative field gadget arithmetic for pseudo-mersenne prime fields

Circuit optimizations:

• #140 - Poseidon Hash Gadget implementation for Tweedle Fr minimizing densities
• #128 - Endomorphism-based scalar multiplication primitive and gadget
• Imported and generalized Hopwood's vbSM (#126) and fbSM (#129) from zcash/zcash#3924

New additions:

• #120 - Import sha256 gadget from https://github.com/zkcrypto/bellman/blob/main/src/gadgets/sha256.rs and implemented RIPEMD160 gadget
• #142 - Implementation of an in-memory Sparse Field-based Merkle Tree