Add helper function to compare commerce_customer_profiles

Based in #2680915: Add source information to copied commerce_customer_profile I decided to write two helper functions to determine if two addresses (specifically the shipping and the billing adress within an order) are equal.

Because I think this might be helpful for other cases I'd like to present these functions to you. Feel free to add them to the project or use them for custom modules:

/**
 * Compares the order shipping address (commerce_customer_shipping) to the order billing address (commerce_customer_billing) and
 * returns true if the shipping address differs from the billing address. If both are equal (doesn't have to mean same ID but same address data) returns false. *
 *
 * @param stdClass|int $commerce_order The commerce order object or ID.
 * @return boolean
 */
function commerce_order_shipping_shipping_address_differs($commerce_order) {
  $commerce_order_wrapper = entity_metadata_wrapper('commerce_order', $commerce_order);
  $commerce_customer_billing_profile = $commerce_order_wrapper->commerce_customer_billing->value();
  $commerce_customer_shipping_profile = $commerce_order_wrapper->commerce_customer_shipping->value();
  return !commerce_customer_profile_equals($commerce_customer_billing_profile, $commerce_customer_shipping_profile);
}

/**
 * Compares two customer profiles and returns true if they are the same (id equals) or both have exactly
 * the same address data. Otherwise returns false.
 *
 * @param stdClass $commerce_customer_profile_a
 * @param stdClass $commerce_customer_profile_b
 * @return boolean
 */
function commerce_customer_profile_equals($commerce_customer_profile_a, $commerce_customer_profile_b) {
  if (!empty($commerce_customer_profile_a->profile_id) && $commerce_customer_profile_a->profile_id == $commerce_customer_profile_b->profile_id) {
    // The two profiles are the same.
    return true;
  }

  if (!empty($commerce_customer_profile_a->commerce_customer_address) && !empty($commerce_customer_profile_b->commerce_customer_address)) {
    if ($commerce_customer_profile_a->commerce_customer_address == $commerce_customer_profile_b->commerce_customer_address) {
      return true;
    }
  }
  return false;
}

The naming currently assumes that these will be added to the commerce_order / commerce_customer modules one day.