- Convert PreferencesSystem & PrefixedPreferencesSystem to use EventDispatcher,
while preserving their existing public API with nonstandard on()/off() APIs
- Remove long-deprecated ability to create resizable bottom panels via
makeResizable() without using createBottomPanel(). (Simplifies code a bit,
but leave in a console error log in case anyone hits this in the future).
- Fix Editor docs about keyboard events
- Docs & error message tweaks from code review
- Simplify assert() calls that are meant to force a debugger pause
Fix bug with detaching one() listeners via off(), spotted thanks to a
question from @Mark-Simulacrum. With unit tests.