Base conversion (and alphabetizing imports)

Racpete can now translate numbers between bases! I also made things alphabetical because it was bothering me. The convert-base code is pretty ugly, I think, but I couldn't figure out a good idiomatic way to do it. Point me in the right direction and I can fix it :)
This, or just pass in (cdr (string-split msg)) and have convert-base take a list of strings.  This is better than second, third, etc because you'll get a contract error with those functions if someone writes a bad string to the channel.  For example, this will crash if I were to write ".c 4".  If you just pass the cdr to convert-base you can verify the length.