fixed problem with dal expressions being parenthesized, thanks Daniel

VERSION

@@ -1 +1 @@
-Version 2.00.0 (2012-08-24 09:53:17) dev
+Version 2.00.0 (2012-08-24 10:04:14) dev

gluon/dal.py

@@ -1317,7 +1317,7 @@ class BaseAdapter(ConnectionPool):
                     tablename,fieldname = item.split('.')
                     new_fields.append(self.db[tablename][fieldname])
                 else:
-                    new_fields.append(Expression(self.db,item))
+                    new_fields.append(Expression(self.db,lambda:item))
             else:
                 new_fields.append(item)
         # ## if no fields specified take them all from the requested tables