Item prompts show "ab-f" instead of "a-f"

[tung]

Title says it all. Caused by https://github.com/DanielT/NitroHack/commit/b13e0e64eea2b5523ecc818f58cba14110e86eb0.

Easiest way to fix it is to increment i1 and i2 in compactify() in place of the old line (like this: https://github.com/tung/NitroHack/commit/6bbba517260cc9e229da78997c56c205a31bf5c3) or just initialize them to 2 instead of 1.