Add negative zoom levels

I did this in views_timelinejs_plugin_style_timelinejs.inc:

$form['timeline_config']['start_zoom_adjust'] = array(
      '#type' => 'select',
      '#title' => 'Zoom Level',
      '#description' => t('Set the default zoom level.'),
      '#options' => array(
	'-4' => t('-4'),
        '-3' => t('-3'),
        '-2' => t('-2'),
        '-1' => t('-1'),
	'0' => t('0'),
... etc

Works great =)