Formatting strings now honor the overlay principle

- The result is that ``1 2 "%s %s" == "1 2"``, not "2 1".  Similarly,
  ``1 2 (|A B| "%(A%) %(B%)") == "1 2"``, because the overlay
  principle holds for binding blocks as well.  It is also used for
  denoting stack profiles (e.g. ``T_ASET T_CONST -> T_ASET`` expects a
  constant on TOS).
Fix presentation of string escape sequences in documentation