Namestring&pathstring returning shared structure

["Scott E. Fahlman" <Fahlman@C.CS.CMU.EDU>]

Signaling an error or doing a copy when someone destructively modifies
the string for a symbol's name is a pain.  If there's a problem here, we
should simply make sure the user never gets his hands on such a string
by copying on the way in and copying again on the way out.  However, I'm
not convinced that there's a problem here, except that the manual does
not state clearly enough that this string is shared, registered in a
hash table, and should not be messed with.  Are people really in danger
of screwing themselves here?

-- Scott