Fix various signature verification issues

[larabr]

• Fix Signatures without signature creation time subpackets are invalid #1137 : throw on signature parsing (e.g. in openpgp.readSignature) if the creation time subpacket is missing from the hashed area.
• Fix Expiration of primary key binding signatures is not honored #1138: SignaturePacket.verify now directly checks for signature expiration and signatures created in the future. This makes it easier to thoroughly check the validity of signatures. Also:
  • openpgp.revokeKey now takes a date to check the provided revocation certificate
  • openpgp.decryptSessionKeys now takes a date to check the validity of the provided private keys
  • whenever a date is used internally, the function accepts a date param to allow for proper time sync.
• Fix missing test for expired signatures #1129 by adding tests for all of the above.
• Like openpgp.generateKey, openpgp.reformatKey now also requires options.userIDs (follow up to Remove Key.prototype.encrypt() and Key.prototype.decrypt() #1285).
• Simplify calling SubKey.isRevoked/update/getExpirationTime by adding the SubKey.mainKey field to hold the reference of the corresponding Key.

Breaking changes in function signatures:

• changes to date param:
  • Key.update(key, config) -> update(key, date, config)
  • Key.applyRevocationCertificate(revocationCertificate, config) -> applyRevocationCertificate(revocationCertificate, date, config)
  • Key.signAllUsers(privateKeys, config) -> signAllUsers(privateKeys, date, config)
  • Key.verifyAllUsers(keys, config) -> verifyAllUsers(keys, date, config)
  • SignaturePacket.constructor(date) -> constructor(void)
  • SignaturePacket.sign(key, data, detached) -> sign(key, data, date, detached)
  • Message.sign(primaryKey, privateKeys, config) -> sign(primaryKey, privateKeys, date, config)
  • Message.decrypt(privateKeys, passwords, sessionKeys, config) -> decrypt(privateKeys, passwords, sessionKeys, date, config)
  • Message.decryptSessionKeys(privateKeys, passwords, config) -> decryptSessionKeys(privateKeys, passwords, date, config)
• removed primaryKey param:
  • SubKey.isRevoked(primaryKey, signature, key, date, config) -> isRevoked(signature, key, date, config)
  • SubKey.update(subKey, primaryKey, date, config) -> update(subKey, date, config)
  • SubKey.getExpirationTime(primaryKey, date, config) -> getExpirationTime(date, config)

[danhab99]

Hey I just noticed that the typedef for revokeKey is not in the typedefs file. Could that be added?

[twiss]

See #1324 :)