CSSTransition: Consistency between initially applied classes and status

[silvenon]

What would you like improved?

The author of #576 expressed confusion around initially applied classes in CSSTransition, where he expected elements to start with *-done classes when mounted (unless both appear and in are true, of course).

This confusion is understandable to me and seems like many people will want and/or expect this behavior, especially because the value of status already suggests this, as it starts with entered/exited (based on initial in).

This would, of course, be a breaking change, but it's something to consider for v5.

[pxwee5]

Depends if mountOnEnter or unmountOnExit is set.
If both is unset, then by default the elements should be rendered (mounted) and display: none.

[constgen]

Not display: none but the same styles as exit-done