1.0.6: conditional pins, Pokemon Tower, plateau statues, cave elevation

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.

main.lua

@@ -376,7 +376,7 @@ mod.events:on("map.reloaded", function(payload)
   if mapId then ChunkMesher.invalidate(mapId) end
 end)
 
-mod.exports.version = "1.0.5"
+mod.exports.version = "1.0.6"
 -- exposed so a companion mod can pin its own tiles' shapes or read the
 -- camera without reaching into this mod's file layout
 mod.exports.lib = V