kinkonkan: Letters outside A-Z don't get encoded

[x-sheep]

The editor allows for 26*4=104 different letters, but only the first 26 get properly encoded. The editor should disable letters outside A-Z, or fix the encoding for all letters.

[ReverM]

What are the possible characters beside A-Z?

[x-sheep]

A-Z uppercase, a-z lowercase, A-Z uppercase except blue, a-z lowercase except blue

[ReverM]

Should be fixed in #645