Fix: missing dependcy on project to check before deleting

htdocs/societe/class/societe.class.php

 <?php
 /* Copyright (C) 2002-2006 Rodolphe Quiedeville <rodolphe@quiedeville.org>
- * Copyright (C) 2004-2014 Laurent Destailleur  <eldy@users.sourceforge.net>
+ * Copyright (C) 2004-2015 Laurent Destailleur  <eldy@users.sourceforge.net>
  * Copyright (C) 2004      Eric Seigne          <eric.seigne@ryxeo.com>
  * Copyright (C) 2003      Brian Fraval         <brian@fraval.org>
  * Copyright (C) 2006      Andre Cianfarani     <acianfa@free.fr>
@@ -42,7 +42,7 @@ class Societe extends CommonObject
     public $element='societe';
     public $table_element = 'societe';
 	public $fk_element='fk_soc';
-    protected $childtables=array("propal","commande","facture","contrat","facture_fourn","commande_fournisseur");    // To test if we can delete object
+    protected $childtables=array("propal","commande","facture","contrat","facture_fourn","commande_fournisseur","projet");    // To test if we can delete object
 
     /**
      * 0=No test on entity, 1=Test with field entity, 2=Test with link by societe