Stair rendering bug

[octylFractal]

I think there is a bug in rendering stairs because the textures for the moss stair don't match up at all.

Originally posted by @octylFractal in #16 (comment)

[proferabg]

@octylFractal This seems to be an issue with all non full-block faces. If you look at the pictures on my issue you can see that none of the stairs are rendered correctly texture wise.