Zkpy

New Features:
- Better error handling
- Added better error handling
- Added ability to export r1cs to a json file
- Added convenience function to fully prove a circuit
- Added ability to export verification code to solidity smart contract
- Added cleanup method for PTau
- Added ability to export / import challenges to 3rd party software
- Can set working directory in Ptau

zkpy provides a Python wrapper over snarkjs and circom. The first release includes the following features:

The `ptau` module allows users to:
- Create and contribute to a powers of tau ceremony
- Apply beacon to a powers of tau ceremony
- Perform phase 2 of a powers of tau ceremony (for groth16)
- Verify a powers of tau file

The `circuits` module allows users to:
- Compile circom circuits
- Generate r1cs, wasm, etc
- Generate witness from input file
- Prove circuits with support for three proving schemes (groth16, PLONK, FFLONK)
- Export verification keys
- Verify proofs with support for three proving schemes (groth16, PLONK, FFLONK)