Forever3DFrames

- Dungeons & raids: the game hides enemy unit data from addons there, so enemy portraits fall back to a classic 2D portrait (left-aligned, ring in the theme colour, grey when dead).
- Gear changes no longer flicker the 3D portrait: the new model loads in the background and replaces the old one once it is ready.
- New targets show their 3D model immediately.
- Out-of-range fade is skipped where the game hides range information.
- Crash protection: a portrait model is never loaded twice in a row.