Synch with Emacs trunk.

Synch with Emacs trunk.
2010-06-08  Michael Albinus  <michael.albinus@gmx.de>
 * auth-source.el (top): Autoload `secrets-list-collections',
 `secrets-create-item', `secrets-delete-item'.
 (auth-sources): Fix tag string.
 (auth-get-source, auth-source-retrieve, auth-source-create)
 (auth-source-delete): New defuns.
 (auth-source-pick): Rewrite in order to avoid 2 passes.
 (auth-source-forget-user-or-password): New parameter USERNAME.
 (auth-source-user-or-password): New parameters CREATE-MISSING and
 DELETE-EXISTING.  Retrieve password interactively, if needed.