As suggested by @sole.

Realised that DirectionalLight is "poluting" the scene graph...

See #2372

Use two component normalScale and set eventual flipping per-model. It's quite ugly but it could do the job if we don't find a better solution.

Do not merge yet.

See #2358

Tweaked UTF8Loader while at it. Not sure what's this new Model() thing for...

This is how compressed textures are supposed to be used:

DXT1 - RGB - opaque textures
DXT3 - RGBA - transparent textures with sharp alpha transitions
DXT5 - RGBA - transparent textures with full alpha range

This is unlikely to work properly in the short term though.

See #2358

Required some tweaking to CanvasRenderer material logic.

Not sure how they lost it.

Thanks to @toji for blog post and DDS utilities.

Fixes #2348

TODO: example textures for alpha formats (DXT3, DXT5).