Massively reorganise the client-side

This commit represents a rather complete rethinking of DConfEngine.

  - the different kinds of sources are now properly abstracted.  This
    will make landing NFS support substantially easier.

  - there is now substantially more internal documentation

  - DConfEngineMessage is gone and replaced with ordinary function calls
    to be implemented by the D-Bus glue code

  - the GDBus glue has been factored out and is now shared between the
    client library and GSettings

  - the "outstanding" queue logic from the GSettings backend is now in
    the engine

  - all changes now go through a single API that accepts a (new)
    DConfChangeset object.  Currently this only supports the current
    operations (ie: setting and resetting).  In the future this object
    will also support the directory operations required by GSettingsList
    and will be the basis for the new approach to implementing the
    'delayed' GSettingsBackend (which will be the method by which those
    two concepts can co-exist).

The (internal) API of the engine changed substantially.  This caused the
following:

  - the libdconf client library has been rewritten in C.  Most of the
    complicated aspects of it (that made it more convenience to use
    Vala) are now gone.

  - during the rewrite of libdconf, the DConfClient API changed a bit to
    look more like a proper GObject.  It now makes GIO-style use of
    thread-default main contexts and uses GObject signals for
    notifications (instead of hand-rolled callbacks).

  - the GSettings backend has been substantially simplified (the
    "outstanding" logic is gone).  No externally-visible changes.

  - the dbus-1 backend has taken a copy of the old engine code for now
    until it can be ported to the new engine and sufficiently tested.
    No externally-visible changes.

  - the dconf commandline tool and dconf-editor required minor changes
    to adjust to the DConfClient API changes

There is a substantial amount of cleaning up and finishing of work to be
done.  There are many stubs remaining.  There are likely still a large
number of bugs.

1 files changed, 3 insertions, 0 deletions

diff --git a/common/dconf-changeset.h b/common/dconf-changeset.h
index 930c09b..de062fa 100644
--- a/common/dconf-changeset.h
+++ b/common/dconf-changeset.h
@@ -32,6 +32,9 @@ typedef gboolean     (* DConfChangesetPredicate)                        (const g
 
 DConfChangeset *        dconf_changeset_new                             (void);
 
+DConfChangeset *        dconf_changeset_new_write                       (const gchar             *key,
+                                                                         GVariant                *value);
+
 DConfChangeset *        dconf_changeset_ref                             (DConfChangeset          *changeset);
 void                    dconf_changeset_unref                           (DConfChangeset          *changeset);