rename lifecycle methods like props

[giladgray]

popoverDidOpen/popoverWillClose etc props are inconsistent with other callback prop names. I propose renaming these to:

• popoverWillOpen => onOpening
• popoverDidOpen => onOpened
• popoverWillClose => onClosing
• popoverDidClose => onClosed

The same changes will happen to the corresponding Overlay props. Note that the existing onClose callback fits nicely in this flow. And I'd happily add an onOpen for consistency.

This is identical to CSSTransitionGroup's lifecycle prop names.

[llorca]

I thought it was pretty elegant to mirror the React component lifecycle naming pattern, I wonder why CSSTG didn't go that route

[llorca]

answer from Gilad: because they're not methods but props

then, what about didOpen willOpen didClose willClose? or onDidOpen onWillOpen onDidClose onWillClose?

[llorca]

do the original proposal

[giladgray]

note that #2335 is also about a popover lifecycle bug