v0.18.0

Added

• interface.generate_and_write_unencrypted_{rsa,ed25519,ecdsa}_keypair (#288)
• interface.generate_and_write_{rsa,ed25519,ecdsa}_keypair_with_prompt (#288)
• interface.import_privatekey_from_file(#288)
• GitHub Action to auto-check upstream changes for vendored ed25519 (#294)

Changed

• interface.generate_and_write_{rsa,ed25519,ecdsa}_keypair require a password
  as first positional argument (#288)
• interface.import_{rsa,ed25519,ecdsa}_privatekey_from_file do not error on
  empty password, but pass it on to lower level decryption routines (#288)
• interface.import_ecdsa_privatekey_from_file supports loading unencrypted
  private keys (#288)
• Revise interface and gpg.functions docstrings, and example snippets, and
  use Sphinx compatible Google Style docstring format (#288, #300)
• Linter-flagged cosmetic changes (#292, #295, #296)
• Bump dependencies: cryptography (#291, #293)
• Bump vendor copy of ed25519 (#299)