* src/gpgme.h.in (struct _gpgme_subkey): Add bit flags can_renc,
can_timestamp, adn is_group_owned. Reduce size of _unused.
* src/keylist.c (set_subkey_capability): Set them.
* tests/run-keylist.c (main): Print them.
* lang/cpp/src/key.h (Subkey::canRenc): New.
(Subkey::canTimestamp): New.
(Subkey::isGroupOwned): New.
* lang/cpp/src/key.cpp: Implement new methods.
(Subkey::isQualified): Print them.
(std::ostream &operator<<): Print them.