event_hub 0.2.1

Dispatch and listen events everywhere and whenever. Also know as `Event Bus`.

[0.2.1] - Update example

• Update the example to use null safety

[0.2.0] - Null safety support

• Added the null safety support

[0.1.1] - Add example

• Created a simple Flutter example

[0.1.0] - Initial release

• Core event hub feature: on & fire.