v0.3.0

This update adds two new middleware to the store by default in development mode:

• redux-immutable-state-invariant, which throws errors if it detects mutations in the state.
• a homegrown middleware which similarly checks for non-serializable values in dispatched actions and store state, and prints console errors with the key path and value if any are found.

These should help detect issues during development.

Also, now that the Redux DevTools Extension has an action stack trace pane included, we enable capturing those during development.

Finally, we've updated to the latest versions of immer (1.9.3) and selectorator (4.0.1).