Add vegetarian dinner option

Change-Id: Ibcda53e07467957f12ccbaf5bc8dc02b9944365f
diff --git a/invoice.php b/invoice.php
index 6c2f57b..3b73799 100644
--- a/invoice.php
+++ b/invoice.php
@@ -36,7 +36,7 @@
         $invoice->addItem( $SERVICE_ACRONYM . ' Registration', $SERVICE_NAME, 1, false, $REGULAR_CONFERENCE_FEE, false, $REGULAR_CONFERENCE_FEE);
     if($user->student) $invoice->addItem('Student Discount', 'Student discount', 1, false, - $STUDENT_DISCOUNT, false, -$STUDENT_DISCOUNT);
     if($user->conference_dinner)  {
-        $invoice->addItem('Conference Dinner', 'The conference dinner will take place on 20 July.', 1, false, $CONFERENCE_DINNER, $CONFERENCE_DINNER * $FULL_VAT, $CONFERENCE_DINNER);
+        $invoice->addItem('Conference Dinner' . ($user->vegetarian_dinner ? " (vegetarian option)" : ""), 'The conference dinner will take place on 20 July.', 1, false, $CONFERENCE_DINNER, $CONFERENCE_DINNER * $FULL_VAT, $CONFERENCE_DINNER);
         $vat_sum += $CONFERENCE_DINNER * $FULL_VAT;
     }
     $lunch_count = 0;