Things that must be done by v0.1.0 release

• Implement the following:
  • reading base58-encoded keys
  • error handling in compress
• Avoid integer division because it's not constant-time
  • divisions with constant divisors are compiled into multiplications, so they are ok
• Separate the following into packages:
  • secp256k1
  • base58
• Make FE, Scalar and Compressed defined types
• benchmarking
• document all functions, packages
  • base58
  • secp256k1
  • bip32
• Add README.md
• Add LICENSE
• Implement fast constant-time multiplication in F_p
  • https://github.com/openssh/openssh-portable/blob/V_9_1_P1/fe25519.c#L196