KMP's remarks about ENDP

[Guy.Steele at CMU-10A]

KMP's remarks are well taken, and his version is certainly more concise.
I do not in fact have a good feel for when to do this in general, but
in trying to write EVAL I found myself using ENDP a lot, and felt that
it would be a lot easier to locate the bug if some context were provided;
providing this context happened always to be easy to do.  But I would
not be unhappy to omit this proposed "feature".
--Guy