gnome-keyring Branch: working on libgcr for importing

[Stef Walter <stefw collabora co uk>]

I've done a bunch more work on libgcr so that we can parse more formats
and handle importers. This will be used by gcr-viewer, and by the work
I'm doing to refactor seahorse. There will be a commonality between
seahorse and applications using libgcr.

This work is in the following branch:

http://cgit.collabora.com/git/user/stefw/gnome-keyring.git/log/?h=import

Bug here:

https://bugzilla.gnome.org/show_bug.cgi?id=659925

I'd like to merge this next week. Let me know if you'd like to look it
over or review any particular part.

Of note:

 * Parsing of OpenPGP packets directly, keys. We parse these to the
   gnupg --with-colons style format so that they can be displayed
   similarly to gnupg keys that come from the keyring.

   This is used for previewing data that will be imported. Obviously
   we mark this parsed data as untrusted and unverified, the gnupg
   web of trust has no bearing on the parsed data.

 * Add a renderer for GnuPG keys so we can view them along side
   certificates and keys.

 * Parsing of OpenSSH public key files (rsa1, rsa2, dsa2). Openssh
   private key files are standard, but the public key files are specific
   to OpenSSH so we add support in the GcrParser for that.

 * Refactor GcrViewerWindow to GcrViewerWidget, so that we can show the
   same widget in a dialog (going to be used in seahorse).

 * Refactor how GcrImporter works. We lookup GcrImporters based on what
   data has been parsed by GcrParser. Implement an importer for smart
   cards and PKCS#11 drivers and another for the GnuPG keyring.

 * Add a GcrImportButton which tracks the usable importers, and performs
   the import operation.

 * GcrParser now reports which format is being parsed, and makes
   available the raw data of the block currently being parsed.

Cheers,

Stef