Add a margins attribute

When chart labels are long (or there are several different labels), they often times are truncated as if they go off the edge of the image. One work-around for this is to add margins to your chart URI like so: &chma=50,50,50,50.

I thought it would be great if you could add margins to a chart URL like this:

    $my_chart['awesome_chart'] = array('#chart_id' => 'awesome_chart',
                                                       '#title' => t('What a great chart'),
                                                       '#type' => CHART_TYPE_PIE_3D,
                                                       '#size' => chart_size(500, 300),
                                                       '#margins' => '50, 50, 50, 50',
                                                       );

I patched the chart.module to allow for this. Patch attachment forthcoming.