core: New function gpgme_op_createsubkey.
* src/genkey.c (createsubkey_start): New. (gpgme_op_createsubkey_start, gpgme_op_createsubkey): New. * src/gpgme.def, src/libgpgme.vers: Add them. * src/engine-gpg.c (gpg_createkey): Factor some code out to ... (gpg_add_algo_usage_expire): new. (gpg_addkey): Implement. * tests/run-genkey.c: Add option --addkey.
- Signed-off-by: Werner Koch <wk@gnupg.org>