Changes in this commit are the consequence of discussion between JPS and YO on the split of business path into business link and trade model path.
The notion of "completion date" does not make much sense anymore in a context in which Business Link are unrelated to dates. Instead, we provide helpers to gather lists and stats of simulation movements of an expanded simulation tree. This should be equivalet for usability at user level, with appropriate reports. The notion of "expected start date and stop date" is kept because it is useful. It is only related to Trade Model Path. A mockup (non working) implementation is provided and supports a bit of recursion so that it can handle the case of transformations. Various security declarations were added.
Next commit will make this work if everyone agrees on interfaces.

git-svn-id: https://svn.erp5.org/repos/public/erp5/sandbox/amount_generator@36833 20353a03-c40f-0410-a6d1-a30d3c3de9de