Changed postscript and dvi bindings to deal with gzipped files

[David Nebauer <davidnebauer switch com au>]

In order to open gzipped postscript and dvi files I changed on my system 
the bindings for those file types:

PS
type/^PostScript            -->       regex/\.([pP][sS])(\.[gG][zZ])?$

DVI
regex/\.([dD][vV][iI])$     -->       regex/\.([dD][vV][iI])(\.[gG][zZ])?$

'run-mailcap' copes fine with either raw or gzipped files.

Not sure if this change is appropriate for all users, but it works for me.

The general problem is that gzipped document formats are not always 
handled gracefully but these files are increasingly turning up as 
documentation.

Regards,
David.