added DIV.add_class, DIV.remove_class, thanks Dulakian, fixed issue 952

VERSION

@@ -1 +1 @@
-Version 2.00.0 (2012-08-23 08:42:44) dev
+Version 2.00.0 (2012-08-23 08:54:31) dev

gluon/html.py

@@ -484,6 +484,19 @@ class XmlComponent(object):
             components += [other]
         return CAT(*components)
 
+    def add_class(self, name):
+        """ add a class to _class attribute """
+        classes = set(self['_class'].split())|set(name.split())
+        self['_class'] = ' '.join(classes) if classes else None
+        return self
+
+    def remove_class(self, name):
+        """ remove a class from _class attribute """
+        classes = set(self['_class'].split())-set(name.split())
+        self['_class'] = ' '.join(classes) if classes else None
+        return self
+
+
 class XML(XmlComponent):
     """
     use it to wrap a string that contains XML/HTML so that it will not be