Adds `when_above` conditional pins, resolved per position in
TileShape.at: one graphic can mean two things (the gates' $32 is both
wall base course and counter front), and a flat pin has to pick one.
Gates get half-height counters and level walls.
Pokemon Tower gains a buildings entry -- it is the drawing the map edge
cuts off, sealed on the north -- and the Indigo Plateau statues are
built like the gym statues.
Fixes: grass stands one full-height clump per tile instead of two
half-cut stubs at different depths; ledge pillars drop to ledge height;
a prop only rides furniture when its own cell is blocked (chairs were
being lifted onto tables); and the caves had water and rock pinned
backwards, which stood the Seafoam sea up as rock and cut trenches
through Mt Moon. No cave tile is below the datum now.
The trees' 2x2-cell drawings unfolded onto the ground as quarter-hull
pancakes -- each tree read as cut in half. The carver is now parametric
over its canvas: a `canopy` anchor tile carves the whole 2x2-cell
drawing as ONE 32px hull, and stamps carry their footprint radius. The
stumps' drawn tops are a cut face, not body: the `stump` class builds
the hull from the bark rows and projects the ring ellipse across the
round flat top, near arc south (stump_cap = the ellipse's drawn rows).
DramaticShape