Move the TextureID to the Rage namespace.

…this took longer than expected.
Some cleanup of the RageTextureManager mess.

The rest won't be so simple.
SurfaceColor is now in Rage.
The SurfacePalette is now in the Rage namespace.
Move the SurfaceFormat over.

Still some more work to go though.
Windows fixes. Also, constexpr plan failed.
Merge branch 'more-rage' into sm6