READ flushing atom delimiters

[MOON at MIT-MC (David A. Moon)]

Well, I discussed that very issue with GSB and decided that on the
whole it was a little bit better to have a variable you could bind
rather than a separate function or an additional optional argument to
READ.  It certainly would not be a win to globally setq the special
variable "to make the whole Lisp work the old way", but my idea is that
certain reader macros, e.g. the LMS open bracket, would bind it on and
then their various internal calls to READ would be automatically
changed.

One example of where a problem occurs with the separate-function
approach (which does not actually show up in LMS I believe) is if
you have something which wants to see the delimiter and calls READ
on an S-expression which turns out to be ' (single-quote) and an
ATOM.  The single-quote macro would have no way of knowing to
call the other version of READ, and hence would swallow the space
after the quoted atom, which presumably is not what the caller wants.