add regression test for recent changes in default handling of checkboxes
# The created form contains several checkboxes, which are
# nasty to handle. When a ceckbox was marked, but is thenq
# # unchecked, this values is NOT returned by the
# browser. The server has to detect by the fact of
# untransmitted values that the instance attribute value
# has to be altered. This is very different to the
# standard cases, where the edited values are transmitted.
#
# The created form below handles also more complex cases:
#
# a) a checkbox box1, where a default is set
# b) a repeated checkbox, where one value is provided
# c) a compound field, where the compound field definition
# contains a default for the sub-component.