Remove dead "language" code from ACC

- This is a feature that never saw the light of day in this form, so get
  rid of its vestigial remnants. (Note that this is NOT the l: print
  formatter that causes the game to look up a string in the LANGUAGE
  lump.)
Add PCD_GOTOSTACK

- It's not used. It's just there as a placeholder.
Fixed: scriptarray[i] += x generated &= x instead