Ed mode: allow re-using given letters arbitrary number of times

[queleok]

See #9 for more info

[queleok]

It would probably be better to change the format of the game in this mode: instead of the square of 16 letters, draw a circle with e.g. 5 letters. The rationale is that there's no sense in generating repetitive letters at all in such a regime, and 16 unique letters are almost 2/3 of the alphabet, which destroys any competitive spirit in players by making the game trivial