* Fixed error message to properly display the archive command when an invalid archive command is detected.
* Check that archive_mode is enabled when archive-check option enabled.
A connection to the primary cluster is still required to start/stop the backup and copy files that are not replicated, but the vast majority of files are copied from the standby in order to reduce load on the master.
Master and standby can both be configured on the backup server and pgBackRest will automatically determine which is the master. This means no configuration changes for backup are required after failing over from a master to standby when a separate backup server is used.
* Make the code more modular and object-oriented.
* Multiple Docker containers can now be created for a single test to simulate more realistic environments.
