• [Cluster] Ignore messages from unknown schemas (e.g. from Sequencer) in EgressPoller.
• [Archive] Ensure that errors from ReplaySession are both captured in the error log and sent to the control session.
• [C] fix double free in aeron_archive_context_t. (#1897)
• [C] Make aeron_subscription_image_release and aeron_subscription_image_retain no op if image is not found in the
  current image list, i.e. handle a case of on_unavailable_image being called and attempting to retain an image that
  was already removed (i.e. C++ Wrapper)).
• [C] invoke the client when in aeron_archive_replay_merge_close. (#1873)
• [C] Handle aeron_archive_encoded_credentials_t being NULL as well as data field being NULL, i.e. treat both as empty credentials.
• [C] Fix race condition in aeron_archive_client reentrancy check, i.e. first acquire lock and then do the check. Use
  mutex to protect aeron_archive_close from concurrent execution.
• [C] Create aeron_mutex_t as recursive/reentrant on POSIX systems, i.e. match behavior on Windows and the Java implementation.
• [C] Fix missing mutex unlock in case of an error.