WordPress Revisional Metabox
Revisional metaboxes in WordPress made easy
WordPress Revisional Metabox is a WordPress PHP library to make revisional metaboxes dead-simple, released as open-source on GitHub. This library is even easier to use than the usual procedural methods for registering custom metaboxes, so I have provided an option to disable revisions on a metabox in case revisions are not appropriate for all your metaboxes.
WordPress 2.6 introduced post revisions for the editor so that authors could save revisions of their content. While this feature has been great for storing revisions of the built-in post title, content, and excerpt fields, it was not very flexible for use by developers to store other data.
In WordPress 4.1, the necessary actions and filters were added to facilitate custom metabox revisions, so that developers can hook into this new functionality, but unfortunately the feature remains prohibitively difficult to use.
That is, unless you use this class to abstract away all the difficulties.
Now WordPress developers can use this amazing functionality for their own projects with ease, and improve the user experience for all.