This patch just adds a bunch of common configuration files to
auto-mode-alist.  I wasn't sure why some of these entries were missing
(e.g. .screenrc) so I thought it prudent to ask before pushing if
there is any reason why we're trying to keep this alist short?

OTOH, I did see that the configuration files for tux racer is in
there... which is fine by me and I suppose pretty useful for those
that have a need to edit that file on a regular basis. ;-)

(FWIW, I imagine there's a good amount of commonly used configuration
files that could usefully be added to this list.  This is just (some
of the) files I found in my $HOME and where having something other
than fundamental-mode would be nice.)

Best regards,
Stefan Kangas