Define _generateRandomId and _generateNextId which are id generation functions.
Remove extraneous Xs. 3 is enough.
Add a string property to Folder named id_generator.
Modify generateNewId to use the new property.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@9295 20353a03-c40f-0410-a6d1-a30d3c3de9de