The `app` folder contains an example of how to use `flutter_quill` and
should therefore be called `example`. But we already have an `example`
folder. Since the code in the existing `example` folder is already in
the `README.md`, I suggest we remove the old `example` folder and
rename `app` to `example`. Another advantage is that `flutter_quill`
becomes consistent with all other packages, since it is very unusual
to have an `app` folder.
* Upgrade upgradable packages
* Apply default null-safety migrations
* Remove hashnode as a dependency and localize its functionality to the package.
Maintenance was done long time ago hence no need to wait for the update
* Localize ui package to reduce maintenance burdens
* Replace universal html with dart:html
* Remove unnecessary checks
* Fix formatting
* Migrate app to null safety
* Enable methods to be nullable
* Fix non-nullable issue with node methods
* Cast as Node
* Use universal html
* Use universal html package to bring in the ImageElement class
* Remove unused imports
* Fix imports on the editor file
* Add key to quill editor
* Remove final from the GlobalKey
* Remove final on GlobalKey
* Remove custom util implementation in favor of quiver
* Fix issue with null on token attrivute
* Remove final hashcode that is replaced by quiver functionality
* Fix merge request
* Fix hit test position in text_line.dart
* Fix null safety errors on text_selection.dart
* Fix sound null safe errors in toolbar.dart
* Import null safe file picker