Tpl::getActivityTypes

private function getActivityTypes(array $activities)
{
	$types = [];
	foreach ($activities as $activity)
	{
		$types[] = $activity['Type'];

		if (!empty($activity['Children']))
		{
			$types = array_merge($types, $this->getActivityTypes($activity['Children']));
		}
	}
	return $types;
}