- Fix AbstractStateMachineFactory so that it does not try
to create transitions with null source or target. Basically we
just skip transition source or target which doesn't belong to
region.
- Change DefaultExtendedState to use ConcurrentHashMap so that
there's less change to get into trouble with concurrency.
- Add statechart for tasks recipe.
- Fix various concepts in TasksHandler and its tests.
- Prepare some examples for docs.
- Fixes#74
