Add char output and fix bug with chars

This fixes a few inconsistencies / bugs with the way we were writing char:

• There was a field of outputs called chars, but
• it actually wrote unsigned char variables, and
• it wrote it as an int

Now there are variables called chars and uchars, where the uchars are unsigned char, and everything is written as the same type it is stored. Hopefully this clears up some things that @frenner was having.