Allow theming of cart menu link title

Patch provides:

• An additional declaration in commerce_cart_theme
• theme_commerce_cart_menu_link_title() which returns the markup originally returned by commerce_cart_menu_item_title()
• Modification of commerce_cart_menu_item_title() to use the new theme function

To use override theme_commerce_cart_menu_link_title in your template.php, e.g.:

function YOURTHEMENAME_commerce_cart_menu_link_title($vars) {
  $quantity = $vars['quantity'];
  return format_plural($quantity, 'My basket (1 item)', 'My basket (@count items)');
}

Patch without commeted out lines

Whoops! missed the default title.

Updated example:

function YOURTHEMENAME_commerce_cart_menu_link_title($vars) {
  
  $quantity = $vars['quantity'];
  if ($quantity > 0) {
    $title = format_plural($quantity, 'My basket (1)', 'My basket (@count)');
  } else {
    $title = 'My basket';
  }
  
  return $title;
}