In several packet classes, we used to store string identifiers for public-key,
aead, cipher or hash algorithms. To make the code consistent and to avoid
having to convert to/from string values, we now always store integer values
instead, e.g. `enums.symmetric.aes128` is used instead of `'aes128'`.
This is not expected to be a breaking change for most library users. Note that
the type of `Key.getAlgorithmInfo()` and of the session key objects returned
and accepted by top-level functions remain unchanged.
Affected classes (type changes for some properties and method's arguments):
- `PublicKeyPacket`, `PublicSubkeyPacket`, `SecretKeyPacket`,
`SecretSubkeyPacket`
- `SymEncryptedIntegrityProtectedDataPacket`, `AEADEncryptedDataPacket`,
`SymmetricallyEncryptedDataPacket`
- `LiteralDataPacket`, `CompressedDataPacket`
- `PublicKeyEncryptedSessionKey`, `SymEncryptedSessionKeyPacket`
- `SignaturePacket`
Other potentially breaking changes:
- Removed property `AEADEncryptedDataPacket.aeadAlgo`, since it was redudant
given `.aeadAlgorithm`.
- Renamed `AEADEncryptedDataPacket.cipherAlgo` -> `.cipherAlgorithm`
- Use PascalCase for classes, with uppercase acronyms.
- Use camelCase for function and variables. First word/acronym is always
lowercase, otherwise acronyms are uppercase.
Also, make the packet classes' `tag` properties `static`.