addChildren = function( contentItem ) {
			allContentItems.push( contentItem );

			if( contentItem.contentItems instanceof Array ) {
				for( var i = 0; i < contentItem.contentItems.length; i++ ) {
					addChildren( contentItem.contentItems[ i ] );
				}
			}
		}
Returns a flattened array of all content items,
regardles of level or type

@private

@returns {void}