Normals in .dds textures

[zer0Kerbal]

From SphericalTanksOld created by zer0Kerbal: zer0Kerbal/SphericalTanksOld#2

per @JadeOfMaar

I just noticed that this commit is not present in the Spherical Tanks release due to my happening to install it while working on TAC LS support for SSPXr. I got MM errors.

Side note: I noticed the normals problem myself. I figured that while they are saved as DDS, they're saved under DXT5 when they should be DXT5_NM which naturally includes some channel swapping.

@hypodronic Bad normals in geometry, not the texture, are usually simply "reversed normals" and result in invisible polygons or polygons that are visible from the wrong side. If the light angles of a part are bad (such that you see the hard edge between every other polygon like on a low-poly sphere) then that's the phong angle-- the light angle in the geometry is too sharp and fixing that requires the model to be ripped or re-exported.