- Support get_single_char/1 in PDT console. This predicate
- If single-char mode is enabled, write "ESC s" over the user output and then wait for two characters, returning the first.
- Output is changed to emit ESC as ESC ESC.
This protocol was designed for PDT by Lukas Degener. The original implementation was partly in Prolog. This is a full C implementation, both for speed.