scroll-1.20150323: TODO

For spells with only 1 component, add a letter frequency table, and make
the charmap be constructed by picking a letter with the desired frequency
that is not otherwise used. This adds a different sort of randomness to the
game.

I've had 2 reports of it crashing after winning the game, with:

scroll: ./Data/Vector/Generic/Mutable.hs:590 (read): index out of bounds (6,6)

The typescript fileG0A3Np on clam should show this happening.