introduce a default render implementation on the base widget, which
add_media and then call the newly introduced method
_render(form, field, formrenderer), abstract of the base widget class.
This allow a litle code factorisation and avoid to forget the call to
add_media in subclasses.
This directory contains extra libraries which are needed
to make cubicweb work.
The mx.DateTime python implementation is directly taken from
the mx.DateTime distribution. The only modification is the
strptime function which has been mocked using the standard
``datetime`` module. (as provided by the python2.5's stdlib)