Create: CAES

Fixes to what the Air Engine looks like and to the Ponder scene that explains it. Nothing about how it works changed, and an 0.1.0 world loads unchanged.

• The flywheel no longer grinds through its own housing. The housing was one solid column with the wheel turning inside its wall: about 2.5px of every arm passed through the casing on each revolution, and the arm corners left the block altogether. The housing is now a foot and a body with an open band between them for the wheel to turn in, and the wheel is four bars whose silhouette barely changes as it turns -- the two rules Create's own Millstone follows. Each layer of the wheel sits on its own plane, so the hub no longer flickers against the spokes, and the housing's brass band is real geometry rather than paint.
• The Air Engine item has its own model. With a band cut out of the housing, inheriting the block model showed the item in hand as a foot and a body with an empty gap between them.
• The piston rod stops a pixel short of the top, so a full stroke no longer fights the housing's own face on an engine with nothing stacked above it -- which for a pipe-fed engine is the normal case.
• The Ponder scene moves. The motor, the shaft and the flywheel were frozen for the whole scene, so pulling the motor out changed nothing on screen while the text narrated a failover, and the piston never stroked. They now turn, the engine holds the speed across the handover the way it really does, and its mode flips on the beat the caption describes.
• A new badge, redrawn as pixel art on the same disc its sibling addons use, so the mod looks like it came out of the game it is for.