This adds a new `useRememberedState()` React hook that effectively allows us to have user interface elements that "remember" their most recent value, even if the UI itself was unmounted at some point. (It only works for the lifetime of the page, however, so it doesn't remember values across page reloads; this is intentional, as I didn't want to have to worry about serialization or schema migration.)
The hook is now used in the randomizer widget and for some of the creature page widgets, to ensure that their settings are preserved more often than not.
Atul Varma