Noteworthy changes in version 1.16.0 (2021-06-24)
* New context flag "cert-expire". [T5505]
* New data flags "io-buffer-size" and "sensitive". [T5478]
* Increase I/O buffer size from 512 to 4k under Windows.
* cpp,qt: Add support for trust signatures. [T5421]
* qt: Add support for flags in LDAP server options. [T5217]
* qt: Fix too high memory consumption due to QProcess. [T5475]
* qt: Do not set empty base DN as query of keyserver URL. [T5465]
* qt: Extend SignKeyJob to create signatures with expiration date.
[5506]
* python: New optional parameter filter_signatures for decrypt.
[T5292]
* Interface changes relative to the 1.15.1 release:
```
gpgme_set_ctx_flag EXTENDED: New flag 'cert-expire'.
cpp: SignKeyJob::setTrustSignature NEW.
cpp: TrustSignatureTrust NEW.
cpp: GpgSignKeyEditInteractor::setTrustSignatureTrust NEW.
cpp: GpgSignKeyEditInteractor::setTrustSignatureDepth NEW.
cpp: GpgSignKeyEditInteractor::setTrustSignatureScope NEW.
cpp: UserID::Signature::isTrustSignature NEW.
cpp: UserID::Signature::trustValue NEW.
cpp: UserID::Signature::trustDepth NEW.
cpp: UserID::Signature::trustScope NEW.
gpgme_key_sig_t EXTENDED: New field 'trust_depth'.
gpgme_key_sig_t EXTENDED: New field 'trust_value'.
gpgme_key_sig_t EXTENDED: New field 'trust_scope'.
GPGME_KEYSIGN_FORCE NEW.
qt: CryptoConfig::entry CHANGED: Added overload; deprecated old
```
(prev: T5225 next: tbd)