Chiavdf

Added

- Replace GMP's primality test function with our own based on Baillie-PSW. The new primality test is based on the 2020 paper ["Strengthening the Baillie-PSW primality test" by Robert Baillie, Andrew Fiori, Samuel S. Wagstaff Jr](https://arxiv.org/abs/2006.14425). The new test works approximately 20% faster than GMP library's mpz_probab_prime_p() function when generating random 1024-bit primes.

Changed

- Refactor form exponentiation, start from top bits of exponent. This slightly improves performance of VDF proof verification.

Fixed

- We've moved to pybind 2.6.2 to avoid a possible shutdown bug in Python 3.9.0.

Added

- Use only Baillie-PSW primality test when hashing to prime. This increases performance of hashing to prime when generating the
discriminant by about 2x.

Added

- We now use a patched gmp 2.6.1 to support Icelake and otherwise have access to faster GCD
- Pybind11 C version of nweso verification

Fixed

- Various race conditions and memory leaks

Added

- Changes to vdf and vdf_client to support the Chia new consensus.
- Now building python 3.9 wheels as well.

Changed

- Now running vdf_client binary tests on CI.

Fixed

- Various memory management and out of bounds read possibilities.

Add debug info.