for properties, define 'read_permission' and 'write_permission'
  in the PropertySheet _properties dict.
for categories, define 'read_permission' and 'write_permission'
  as properties of the BaseCategory in portal_categories.

it should support TALES expressions, if you want to use a script
  that returns a permission based on the portal type.

Also renamed "klass" to "property_holder" as requested by Yoshinori.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@3325 20353a03-c40f-0410-a6d1-a30d3c3de9de