Add support for the Stacked Bar and Stacked Bar 3D renderers in the chart macro

This feature has been available on the previous Radeox macro: http://extensions.xwiki.org/xwiki/bin/view/Extension/Charting+Samples
This feature would allow users that have been using the previous macro to migrate their old pages from syntax 1.0 to a newer syntax and start using the chart macro.