Contributed by Patrick Gerken: It is now possible to hide the "day" subfield

of a DateTimeField, and to decide if the date should be generated as the first
or last day of the selected month.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@10196 20353a03-c40f-0410-a6d1-a30d3c3de9de