* lang/cpp/src/gpgmefw.h (gpgme_revocation_key_t): New forward
declaration.
* lang/cpp/src/key.cpp, lang/cpp/src/key.h (class Key): New methods
revocationKey, numRevocationKeys, revocationKeys.
(class RevocationKey): New.
(swap): New overload for RevocationKey.
(operator<<): New overload for RevocationKey.
* lang/cpp/src/key.cpp (operator<<): Add information about revocation
keys to the output stream for Key.
* lang/cpp/tests/run-keylist.cpp (main): Don't output Key if nextKey
failed, e.g. at the end of the key listing.