Unrecognized \ sequences and Elisp

[Neil Jerram]

The recent change to signal an error for "unrecognized" \ sequences
has negatively affected the Elisp translator, because Elisp code often
uses "\(" in doc strings.  (I think this is when the "(" would
otherwise be in column 0, to avoid Emacs thinking that it is the start
of a new defun.)

What should we do about this?  Is it reasonable to again allow "\(" as
a special case - perhaps only when SCM_ELISP_READ_EXTENSIONS is
defined - or do we need to implement the Elisp reader completely
independently of the Guile reader?

        Neil