Bug fix

Avoid a few bugs in dispose() state.

First release

0.6.1 - 20190604

Improves package health.

0.6.0 - 20190604

Support Customized content widgets.
Support auto adjusts board radius.
Add examples.

0.5.0 - 20190604

Implement basic progress button function and animation.
Use onProgress call back onPressed and returns a result handler function to indicate animation is completed and you are ready to go.