[FIXED] Glider in 1-pixel-shaft ignores updraft [BUG]

[Simon]

Porcupine reads glider code, porcupine quills go up, porcupine carves out test map to prove hunch.

You have plastered the entire map with updrafts.
You have a n-pixel-wide vertical shaft of air, with vertical walls at each sides, for n > 0.
You have a glider in this shaft.

Observed: The glider ascendes in each shaft of thickness 2, 3, 4, ..., and descends in the 1-pixel-wide shaft.
Expected: The glider ascends in each such shaft.

-- Simon

[Nepster]

Thanks. Now fixed.