[FIX] allow to use the rowspan attribute on the group tag

lp bug: https://launchpad.net/bugs/323551 fixed

bzr revid: stephane@tinyerp.com-20090202071347-af02011b97ro5237

bin/addons/base/rng/view.rng

@@ -272,6 +272,7 @@
             <rng:optional><rng:attribute name="attrs"/></rng:optional>
             <rng:optional><rng:attribute name="col"/></rng:optional>
             <rng:optional><rng:attribute name="colspan"/></rng:optional>
+            <rng:optional><rng:attribute name="rowspan"/></rng:optional>
             <rng:optional><rng:attribute name="position"/></rng:optional>
             <rng:optional><rng:attribute name="expand"/></rng:optional>
             <rng:optional><rng:attribute name="states"/></rng:optional>