WowAce

John Wellesz:
    - Create a sub-frame under each nameplate's base frame and hook its OnShow and OnHide script handlers instead of hooking those of the base nameplate as suggested by Adirelle. It's more reliable and might fix incompatibilities with old nameplate add-ons.
    - Do not rehook the base nameplate frames if an add-on hooked them using AceHook-3.0 (which uses SetScript()). This fixes incompatibilities with Aloft.