latin: assign polyomino shapes (tetris pieces)

latin: assign polyomino shapes (tetris pieces)

System to encode messages in tetris drops, mapping 19 fixed tetrominoes
<https://en.wikipedia.org/wiki/Tetromino?oldid=1032015917> to corresponding
letters for unrotated shapes I O T L S Z, rotating to match similar
appearances for A F N P.

To distinguish all 26 letters, include fixed polyominoes with fewer cells
<https://en.wikipedia.org/wiki/Polyomino?oldid=1037069367> for 28 variants:
trominoes to optionally distinguish longer approximates K>Q, F>V, U>W, H>X,
and shorter I cuts for J and Y (substitutable by full line).