Release 0.8.3

Release 0.8.3 is a minor release and contains several bugfixes mostly related to HierarchicalStateMachine:

• Feature #473: Assign is_<model_attribute>_<state_name> instead of is_<state_name> when model_attribute != "state" to enable multiple versions of such convenience functions. A warning will be raised when is_<state_name> is used. (thanks @artofhuman)
• Similarly, auto transitions (to_<state_name>) will be assigned as to_<model_attribute>_<state_name>. to_<state_name> will work as before but raise a warning until version 0.9.0.
• Bugfix: allow_substates did not consider enum states
• Feature: Nested enums can now be passed in a dict as children with initial parameter
• Bugfix #449: get_triggers/get_transitions did not return nested triggers correctly (thanks @alexandretanem)
• Feature #452: Improve handling of label attributes in custom diagram states and TransitionGraphSupport (thanks @badiku)
• Bugfix #456: Prevent parents from overriding (falsy) results of their children's events (thanks @alexandretanem)
• Bugfix #458: Entering the same state caused key errors when transition was defined on a parent (thanks @matlom)
• Bugfix #459: Do not remove current timeout runner in AsyncTimeout to prevent accidental overrides (thanks @rgov)
• Rewording of State.enter/exit debug message emitted when callbacks have been processed.
• Bugfix #370: Fix order of before_state_change/before and after/after_state_change in AsyncMachine (thanks @tzoiker and @vishes-shell)
• Bugfix #470: Graph.get_graph() did not consider enum states when show_roi=True (thank @termim)