Add to reports the possiblity to invoke a method on the report context in order to find the object on which the form should be applied to. This is used by the new documentation system to build DocumentationHelper instances (which do not exist within the ZODB) for each URI of each report section.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@17611 20353a03-c40f-0410-a6d1-a30d3c3de9de