Have Tabs2 fire onChange even when current tab is clicked

[jkillian]

Basic idea here is that in some use cases, clicking a tab should take users back to top-level content after they've drilled down into more specific content. If the currently selected tab is clicked, the component can fire onChange / possible rerender.

I'm not 100% sure yet, but this behavior can be opt-in via a prop if it turns out to be a breaking change.