gnome-keyring libgck: Will merge gck-work branch soon

[Stef Walter <stefw gnome org>]

libgck is a GObject wrapper of PKCS#11. Still pretty low level but makes
PKCS#11 easier to use from GNOME or GTK+ apps.

 * GCK stands for "Gobject CryptoKi".

 * gnome-keyring-daemon these GObject PKCS#11 wrappers internally.

 * libgck a massive cleanup and refactoring from libgp11. Learned
   lots of lessons from the shortcomings in the libgp11 API.

 * Currently lives in the gnome-keyring git module, but may be
   split into its own module in the future.

This is currently on the 'gck-work' branch in gnome-keyring at
git.gnome.org.

I'd like to merge this into gnome-keyring master before GNOME 2.91.1
development release (next week).

I appreciate any and all help looking over the API for usability,
bindability, sanity.

Cheers,

Stef