[#11] Added antialiasing

[datinc]

This adds antialiasing so that the curtain demo looks much nicer.

[Ciechan]

While your patch is certainly the most robust fix, it's quite an expensive way to do AA. Instead one should simply use a container layer that's one point larger in each direction. This will provide AA essentially for free, similarly to how it's done with pseudo antialiasing done for UIImageView by using UIImage with one pixel transparent border.