issue 618, input with error gets class invalidinput, thanks David

VERSION

@@ -1 +1 @@
-Version 1.99.4 (2012-01-16 21:58:15) stable
+Version 1.99.4 (2012-01-16 22:03:22) stable

gluon/html.py

@@ -1611,6 +1611,7 @@ class INPUT(DIV):
         if name and hasattr(self, 'errors') \
                 and self.errors.get(name, None) \
                 and self['hideerror'] != True:
+            self['_class'] = (self['_class'] and self['_class']+' ' or '')+'invalidinput'
             return DIV.xml(self) + DIV(self.errors[name], _class='error',
                 errors=None, _id='%s__error' % name).xml()
         else: