thingatpt.el URL scheme part regexp fix

[Markus Holmberg <ens97mhg@cs.umu.se>]

This bug report will be sent to the Free Software Foundation,
 not to your local site managers!!
Please write in English, because the Emacs maintainers do not have
translators to read other languages for them.

In GNU Emacs 20.7.2 (i386-debian-linux-gnu, X toolkit)
 of Tue Apr  9 2002 on lilac modified by Debian
configured using `configure  --prefix=/usr --with-gcc --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --sharedstatedir=/var/lib --localstatedir=/var/lib --with-pop=yes --with-x=yes --with-x-toolkit=yes --with-xim=yes --enable-ipv6 i386-debian-linux-gnu'

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

thingatpt.pl fails to recognize URL schemes other than the common ones
(http, ftp ...) and prepends a default scheme prefix though there
already exists one.

Trying to launch a RealPlayer URL "rtsp://host/stream.ra" using
browse-url yields "http://rtsp://host/stream.ra" (note the
unappropriately prepended "http://").

The following patch updates thingatpt.el to recognize URL schemes
according to RFC1738 (see BNF on last line of page 16). It looks
correct to me.

I can be contacted at markush at acc dot umu dot se.

--- thingatpt.el.orig	Thu Nov 18 10:23:58 1999
+++ thingatpt.el	Wed Oct  2 00:35:24 2002
@@ -212,9 +212,7 @@
 ``thing-at-point-url-regexp''.")
 
 (defvar thing-at-point-url-regexp
-  (concat
-   "\\(https?://\\|ftp://\\|gopher://\\|telnet://\\|wais://\\|file:/\\|s?news:\\|mailto:\\)"
-   thing-at-point-url-path-regexp)
+  (concat "[a-z0-9+-.]+:" thing-at-point-url-path-regexp)
   "A regular expression probably matching a complete URL.")
 
 (defvar thing-at-point-markedup-url-regexp