// links : list of external links to add in the menu. An example is the best
// than a long explanation :
// Advanced usage:
//  You can also used special options. Instead to pass a string like parameter value
//  you can pass a array with different optional parameter values
//  $conf['links'] = array(
//    'http://piwigo.org' => array('label' => 'PWG website', 'new_window' => false, 'eval_visible' => 'return true;'),
//    'http://piwigo.org/forum' => array('label' => 'For ADMIN', 'new_window' => true, 'eval_visible' => 'return is_admin();'),
//    'http://piwigo.org/ext' => array('label' => 'For Guest', 'new_window' => true, 'eval_visible' => 'return is_a_guest();'),
//    'http://piwigo.org/downloads' =>
//      array('label' => 'PopUp', 'new_window' => true,
//      'nw_name' => 'PopUp', 'nw_features' => 'width=800,height=450,location=no,status=no,toolbar=no,scrollbars=no,menubar=no'),
//    );
// Parameters:
//  'label':
//    Label to display for the link, must be defined
//  'new_window':
//    If true open link on tab/window
//    [Default value is true if it's not defined]
//  'nw_name':
//    Name use when new_window is true
//    [Default value is '' if it's not defined]
//  'nw_features':
//    features use when new_window is true
//    [Default value is '' if it's not defined]
//  'eval_visible':
//    It's php code witch must return if the link is visible or not
//    [Default value is true if it's not defined]
//
// Equivalence:
//  $conf['links'] = array(
//    'http://piwigo.org' => 'PWG website',
//    );
//  $conf['links'] = array(
//    'http://piwigo.org' => array('label' => 'PWG website', 'new_window' => false, 'visible' => 'return true;'),
//    );