The official website of this project is: http://galleria.io
Contao repository : http://contao.org/en/extension-list/view/galerie.html
This version use the jQuery extension. You should modify your page layouts by selecting “use jQuery” under “Advanced Settings”. Choose “use jQuery and MooTools” if you want to use this two scripts simultaneously in your pages.
If you want to use "galerie" with the insert tag {{insert_content::*}}, you must install the extension "inserttags_js_support" before (http://www.contao.org/en/extension-list/view/inserttags_js_support.html).
The master branch is used for the version compatible with Contao 3.