* Fix `Engine` to support flows that are nested dictionaries.
0.4.9
* Add `profile` argument to the `Engine` constructor. When this argument is set to `True`, the simulation, including any parallel processes, will be profiled by `cProfile`. Once `Engine.end()` is called, the profile stats will be saved to `Engine.stats` for analysis.
0.4.8
* Remove `self._run_steps()` from `Engine.apply_update` if `view_expire`.
0.4.7
* `view_expire` flag for `_add` and `_delete` updates as well.
0.4.6
* deepcopy mother state upon division so daughter states are ensured to not reference the same objects. * improve `_get_composite_state` to avoid recursive deepcopy. * add `view_expire` flag in `Store.apply_update`, and have `Engine` use this to trigger `self.state.build_topology_views`.
0.4.5
* Fixed a major bug introduced by `topology_view` in v0.4.3, which had glob (*) schema unable to view sub-stores. * `dict_value` updater added to `updater_registry`.