Replace library sources with git submodules

[Tolsi]

All that libraries were found on the github, so we can make them the git submodules, for example:

• https://github.com/agl/curve25519-donna
• https://github.com/floodyberry/ed25519-donna
• https://github.com/bitcoin/libbase58
• https://github.com/BLAKE2/BLAKE2
• https://github.com/B-Con/crypto-algorithms (for sha256)
  ...?