Two immovable bodies would never set their overlap data, even if an overlap only check was being made. As this is useful data to have this has been changed. Two immovable bodies will still never separate from each other, but they _will_ have their `overlapX` and `overlapY` properties calculated now.
* Body.setCircle allows you to define a Body as using a circle to collide with instead of a rectangle. You can set the radius of the collision circle and an offset.
* Body.render now renders both circle and rectangle body shapes to the Debug canvas.
* World.intersects has been updated to support both circle and rectangle body shapes, and supports quick-paths for circle vs. circle and rect vs. rect checks.
* World.circleBodyIntersects is a new method that checks for intersection between a Body that has been defined as a circle, and a normal rectangle based Body. This is used internally by World.intersects, but exposed for direct calls as well.
Sprites with Arcade Physics bodies that had `collideWorldBounds` enabled would be moved to the wrong position if you restarted a State (or swapped to a new State) that reset the world bounds (thanks @vulvulune #1775)
Physics.Arcade.sort now calls one of four functions: sortLeftRight, sortRightLeft, sortTopBottom and sortBottomTop. Each of which takes 2 Sprites as arguments.
Physics.Arcade.sort now doesn't bail out if the Group contains a mixture of physics and non-physics enabled objects, as the Group hash is now only ever populated with physics enabled objects. Also the sort comparison functions no longer return -1 if the bodies are invalid, but zero instead (#1721)
There are 3 other directions available (`RIGHT_LEFT`, `TOP_BOTTOM` and `BOTTOM_TOP`) and which one you need will depend on your game type. If you were making a vertically scrolling shoot-em-up then you'd pick `BOTTOM_TOP` so it sorts all objects above and can bail out quickly.
More importantly you can switch the `sortDirection` at run-time with no loss of performance. Just make sure you do it *before* running any collision checks. So if you had a large 8-way scrolling world you could set the `sortDirection` to match the direction the player was moving in and adjust it in real-time, getting the benefits as you go. My thanks to Aaron Lahman for inspiring this update.
ArcadePhysics.moveToPointer no longer goes crazy if the maxTime parameter is given and the Sprite is positioned in a larger game world (thanks @AnderbergE #1472)
