encapsulated tasks

0.8.12

• Officially release and document "Encapsulated Tasks", which
  are tasks that can maintain/mutate their own state without
  having direct access to the host object's state. In conjunction
  with Derived State, this allows for some nice patterns for
  containing state/logic/mutations within the tasks, rather
  than requiring that state/events generated by tasks live on /
  bleed into the host objects.