to get rid of seams in repeating patterns. https://github.com/mapbox/mapbox-gl-styles/issues/50#issuecomment-86159351
- OpenGL ES 2 doesn't allow NPOT textures with wrap-around - The Sprite object reported the map's pixelRatio, even though it loaded @2x assets - Copying icons from the sprite into the atlas now uses bilinear scaling to scale up to the actual size