use html ⇒ symbol for @result

[Per Bothner]

It would be nice to use standard HTML4 symbols for some of the special
texinfo symbols.  Specifically, @result.  I suggest using ⇒ aka
U+21D2 aka "rightwards double arrow".  This also works for docbook,
since docbook also defines many (most? all?) of the HTML4 entities,

Attached is a patch which seems to work.  (Only tested for docbook,
which I then converted to html using my own scripts.)

Some issues to consider:
(1) What about other glyphs, such as @expansion?
There is also a "long rightwards double arrow" but that
is a relatively recent addition to Unicode, and does not
appear in HTML4.  One could use → (a single arrow);
use "==>" as now, or use &rArr for @expansion as well.
I don't feel strongly about this.

(2) What about older pre-HTML4 browsers?  (I don't know when
&rArr was added to HTML.)  Personally, I don't care.

(3) What about buggy browsers, that don't support ⇒
properly.  Again, I don't care.

(4) What about text-mode browsers?  Well, elinks seems to
handle ⇒ fine, when run under gnome-terminal, on
Fedora Core 6.  There are very few people who use text-mode
browsers, and if you're reading texinfo documentation on a
terminal you'd be using 'info' (or emacs info mode) anyway.
So I can't see this as a real concern either.  It's time
to accept we're in a Unicode world.
--
        --Per Bothner
address@hidden   http://per.bothner.com/

Index: cmds.c
===================================================================
RCS file: /sources/texinfo/texinfo/makeinfo/cmds.c,v
retrieving revision 1.67
diff -u -r1.67 cmds.c
--- cmds.c      11 Dec 2006 14:59:59 -0000      1.67
+++ cmds.c      6 Jan 2007 03:40:06 -0000
@@ -1579,7 +1579,10 @@
 cm_result (int arg)
 {
   if (arg == END)
-    add_word (html ? "=>" : "=>");
+    if (html || docbook)
+      xml_insert_entity ("rArr");
+    else
+      add_word ("=>");
 }
 
 /* What an expression expands to. */