This template is used to print a single grouping in a view.
It is not actually used in default Views, as this is registered as a theme
function which has better performance. For single overrides, the template is
perfectly okay.
Variables available:
$view: The view object
$grouping: The grouping instruction.
$grouping_level: Integer indicating the hierarchical level of the grouping.
$rows: The rows contained in this grouping.
$title: The title of this grouping.
$content: The processed content output that will normally be used.