HELP FLATLISTIFY                                           A. Sloman Feb 1983

    flatlistify(list) -> list;

This procedure takes a list which may contain embedded lists or vectors.  It
returns a new list containing no embedded lists or vectors.  Instead all such
structures are replaced by first the word "[" or "{", then all the components
(flatlistified, if necessary) then "]" or "}".  The brackets "[" "]" are used
for embedded lists, and "{" "}" for vectors. E.g.

    vars x;
    [a [ b c { d e [ f ] g }] h] -> x;
    vars y;
    flatlistify(x) -> y;
    x =>
    ** [a [b c {d e [f] g}] h]
    y =>
    ** [a [ b c { d e [ f ] g } ] h]
    length(x) =>
    ** 3
    length(y) =>
    ** 14
