Fix hiding auras in rare cases

The problematic case was reported via a wowace message thread and
involved a Cooldown Progress Dark Soul aura in a dynamic group,
which wouldn't hide even though the progress was done.
See: http://pastebin.com/1KPwbrt3

Collpase should also reset region.show so that a previous Expand,
that hasn't yet happened is canceled. Do the same for Expand after
Collapse.