Effect 2 (No Midtexture Skew) now toggles off skewing for midtextures on...

Effect 2 (No Midtexture Skew) now toggles off skewing for midtextures on single-sided lines, which was what was intended for them to begin with apparently.

This means the current skewing-by-default effect isn't changed, and OpenGL's equivalent code doesn't have to be touched since apparently it was already like that.