This patch made its first step as a way to teach qq to also work on
python3. However the differences in str / unicode and escapes in between
py2 / py3 quickly popped out and then it became easier to just handle
whole escaping logic myself.

The implementation is based on

	kirr/go123@c0bbd06e

and byproduct of manual handling is that now we don't escape printable
UTF-8 characters.