Added the "TiledGraphic" property to particles. Only works for particles with a screen-type focus (background/midground/foreground) and aren't an emitter. It is used for background images that move around, letting you achieve a panning background with just a single particle.
Details: This property creates 3 copies of the sprite to the left/above/left and above of the main sprite, and repositions the sprite and its copies to ensure they're always covering the screen. Make sure you're using a screen-sized graphic (or larger) or you'll get weird-looking results. Changes to the frame, zooms or angle properties of the particle aren't applied to the copies, but why would you change those for a panning background? All other properties, including opacity and colour, are applied to the copies.