Flopsy

This release changes the Imgui bindings distribution that the Inspector uses from `pyimgui` to `imgui_bundle`. There are a few differences in the way Imgui datatypes are implemented.

Also, in advance of the first release of the Imgui backend for [mfp](https://github/com/bgribble/mfp), a number of changes were made to allow the inspector to work in an existing Imgui app, and also to support new use cases and fix bugs that I found during the MFP work.

The `mutates` decorator wraps a method that changes state without calling `dispatch`, i.e. a "legacy" method.

* Add examples/demo.py, a working demo script
* Unlisten from state changes when closing the inspector
* Allow for action types without a reducer, and sagas that don't care about state change