Implement line texturing and allow force nearest (softgpu)

This allows forcing nearest, which is actually much faster (though uglier.)  Forcing linear can workaround #4853 but causes other artifacts.

Also reorganizes code so that lines and points can texture.  Hexyz Force uses textured lines in its (not very good looking imho) title appearance animation.  Performance is pretty awful when it's doing this but this makes it better and actually render somewhat correctly.

Also applies #5122 since I changed the code and figure it might be right (I'm really not sure, but if it fixes a game I guess it probably is.)

-[Unknown]