\!: Save and restore this for @tex.

From: Jean-Pierre Moreau <jpmoreau@ciframedical.com>
Date: Fri, 22 Aug 1997 16:47:36 -0400

texinfo.tex

@@ -55,6 +55,7 @@
 \let\ptexdots=\dots
 \let\ptexend=\end
 \let\ptexequiv=\equiv
+\let\ptexexclam=\!
 \let\ptexi=\i
 \let\ptexlbrace=\{
 \let\ptexrbrace=\}
@@ -3529,18 +3530,23 @@ width0pt\relax} \fi
   \catcode`\>=12
   \escapechar=`\\
   %
+  \let\b=\ptexb
+  \let\bullet=\ptexbullet
+  \let\c=\ptexc
   \let\,=\ptexcomma
+  \let\.=\ptexdot
+  \let\dots=\ptexdots
+  \let\equiv=\ptexequiv
+  \let\!=\ptexexclam
+  \let\i=\ptexi
   \let\{=\ptexlbrace
   \let\}=\ptexrbrace
-\let\.=\ptexdot
   \let\*=\ptexstar
-\let\dots=\ptexdots
+  \let\t=\ptext
+  %
   \def\endldots{\mathinner{\ldots\ldots\ldots\ldots}}%
   \def\enddots{\relax\ifmmode\endldots\else$\mathsurround=0pt \endldots\,$\fi}%
   \def\@{@}%
-\let\bullet=\ptexbullet
-\let\b=\ptexb \let\c=\ptexc \let\i=\ptexi \let\t=\ptext
-%
 \let\Etex=\endgroup}
 
 % Define @lisp ... @endlisp.