Theme package mime type in 2.18

[Thomas Wood <thos gnome org>]

One of the new features in GNOME 2.18 is that the theme manager will be 
associated with a specific mime type for "theme packages" 
(application/x-gnome-theme-package, file suffix ".gtp").

There is nothing new here, as it uses exactly the same gzipped tarball 
format and directory layout as we have been using in the past, but now 
we can specifically open and install themes with the theme manager.

If anyone has any final comments on the chosen mime-type and extension, 
now would be a good time to make them. Please note that an extension 
such as ".theme" was not chosen because it is already in use elsewhere 
on the desktop, and is also too generic to specify what the file 
actually is.

See these bugs for more information:

* http://bugzilla.gnome.org/show_bug.cgi?id=393697
* http://bugzilla.gnome.org/show_bug.cgi?id=149346

-Thomas