Introduce a new configuration section in XWiki Administrator for Comparing Versions in History tab

Currently, the compared changes in the document are represented in "Raw" tab (which is active default) and provided by object class properties. Which isn't as informative and user-friendly as "Render" tab.

IMHO, it can be customized from the source template changesdoc.vm.

But having "Render" tab first one and active by default for compared changes as a result, rendering such content can be a resource-intensive process, especially for complex documents with many macros.

That's why this option has to be optional and only changeable from XWiki Adminstrator section (for instance from Content column)