Noteworthy changes in version 1.15.0 (2020-11-12)
* New function gpgme_op_setexpire to make changing the expiration
easier (requires GnuPG 2.1.22). [T4999]
* New function gpgme_op_revsig to revoke key signatures (requires
GnuPG 2.2.24). [T5094]
* Support exporting secret keys. [T5046]
* cpp: Support for set expire operations in the C++ bindings. [T5003]
* cpp: Support for revoking key signatures in the C++ bindings. [T5094]
* qt: Extended ChangeExpiryJob to support changing the expiry of
subkeys. [T4717]
* qt: Extended QuickJob to support revoking of key signatures. [T5094]
* qt: Added QDebug stream operator for GpgME::Error.
* Require a somewhat newer version of libgpg-error (1.36).
* Interface changes relative to the 1.14.0 release:
```
gpgme_op_setexpire_start NEW.
gpgme_op_setexpire NEW.
gpgme_op_revsig_start NEW.
gpgme_op_revsig NEW.
GPGME_REVSIG_LFSEP NEW.
cpp: Context::setExpire NEW.
cpp: Context::startSetExpire NEW.
cpp: EngineInfo::Version::operator<= NEW.
cpp: EngineInfo::Version::operator>= NEW.
cpp: EngineInfo::Version::operator!= NEW.
cpp: StatusConsumer NEW.
cpp: StatusConsumerAssuanTransaction NEW.
cpp: Context::cancelPendingOperationImmediately NEW.
cpp: Context::revokeSignature NEW.
cpp: Context::startRevokeSignature NEW.
cpp: UserID::Signature::operator< NEW.
qt: operator<<(QDebug debug, const GpgME::Error &err) NEW.
qt: QuickJob::startRevokeSignature NEW.
qt: QuickJob::result CHANGED: Made params 'auditLogAsHtml'
and 'auditLogError' optional.
```