getActivityRuntimeEnvironment is changed to return an ActivityRuntimeEnvironment
instance instead of a dict (and this value is now stored in a transactional
variable, for automatic cleanup).
This object allow activities to change default behaviour of CMFActivity if an
error happens. In the future, this object could also allow executed activity to
inspect its related Message object.

In case of infinite retry, notify the user when the default limit is reached.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@32879 20353a03-c40f-0410-a6d1-a30d3c3de9de