* if delete underlying callable from container, delete it's ZScheduleEvent (fancy
  manage_beforeDelete ...)

* catch Zope's atexit and call the timer's stop function (ie for Crontab, cancel it...)

* fix SecurityInfo Class "Crontab" had conflicting security declarations etc

* implement Vixie Cron's day_of_week, day_of_month inclusivity

* write ZScheduleEvent timer test cases, as there's surely a few bugs here :(

* test zope dispatchers ...
