title: Change formatted address order no longer working
body: <p>Something appears to have changed in the new version of WooCommerce, this snippet to change the order of the items in a formatted address used to work fine....</p>
  
  <pre><code>add_filter( 'woocommerce_order_formatted_billing_address' , 'woo_custom_order_formatted_billing_address' );
  
  /**
   * woo_custom_order_formatted_billing_address
   *
   * @access      public
   * @since       1.0 
   * @return      void
  */
  function woo_custom_order_formatted_billing_address() {
  
      $address = array(
          'first_name'    =&gt; $this-&gt;billing_first_name,
          'last_name'     =&gt; $this-&gt;billing_last_name,
          'company'       =&gt; $this-&gt;billing_company,
          'address_1'     =&gt; $this-&gt;billing_address_1,
          'address_2'     =&gt; $this-&gt;billing_address_2,
          'city'          =&gt; $this-&gt;billing_city,
          'state'         =&gt; $this-&gt;billing_state,
          'postcode'      =&gt; $this-&gt;billing_postcode,
          'country'       =&gt; $this-&gt;billing_country
      );
  
      return $address;
  
  }
  </code></pre>
  
  <p>But now it returns the following error...</p>
  
  <p>Fatal error: Using $this when not in object context in</p>
  
  <p>Can anyone point me in the right direction of either what is going wrong or an alternative way of achieving it?</p>