* Containers now use a squid proxy for apt/yum to speed builds.
* Obsolete containers are removed by the <br-option>--vm-force</br-option> option.
* Greatly reduced the quantity of Docker containers built by default. Containers are only built for PostgreSQL versions specified in db-minimal and those required to build documentation. Additional containers can be built with --db-version=all or by specifying a version, e.g. --db-version=9.4.
Allow hidden options to be added to a command. This allows certain commands (like apt-get) to be forced during the build without making that a part of the documentation.
* Recommended install location for pgBackRest modules is now /usr/share/perl5 since /usr/lib/perl5 has been removed from the search path in newer versions of Perl.
* Added instructions for removing prior versions of pgBackRest.
* Fix usage of sprintf() due to new constraints in Perl 5.22. Parameters not referenced in the format string are no longer allowed. (Fixed by Adrian Vondendriesch.)
Added an execution cache so that documentation can be generated without setting up the full container environment. This is useful for packaging, keeps the documentation consistent for a release, and speeds up generation when no changes are made in the execution list.
Release notes are now broken into sections so that bugs, features, and refactors are clearly delineated. An "Additional Notes" section has been added for changes to documentation and the test suite that do not affect the core code.
The change log was the last piece of documentation to be rendered in Markdown only. Wrote a converter so the document can be output by the standard renderers. The change log will now be located on the website and has been renamed to "Releases".
