Cleanups: fix deprecated g_type_class_add_private()

- use G_DECLARE_ and G_DEFINE_ macros
- move all data into ClassNamePrivate
- use _get_instance_private()

This should not introduce any functional changes or breakage.

Skipped two classes (EekKeyboard and EekboardContextService) for now in
order not to break the build.

These two classes are used in some very funky WIP code that tries to
circumvent encapsulation.

(Funky code is in eekboard/key-emitter.c and eekboard/eekboard-context-service.c)

eekboard/eekboard-service.h

@@ -28,30 +28,7 @@ G_BEGIN_DECLS
 #define EEKBOARD_SERVICE_INTERFACE "sm.puri.OSK0"
 
 #define EEKBOARD_TYPE_SERVICE (eekboard_service_get_type())
-#define EEKBOARD_SERVICE(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), EEKBOARD_TYPE_SERVICE, EekboardService))
-#define EEKBOARD_SERVICE_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), EEKBOARD_TYPE_SERVICE, EekboardServiceClass))
-#define EEKBOARD_IS_SERVICE(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), EEKBOARD_TYPE_SERVICE))
-#define EEKBOARD_IS_SERVICE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), EEKBOARD_TYPE_SERVICE))
-#define EEKBOARD_SERVICE_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), EEKBOARD_TYPE_SERVICE, EekboardServiceClass))
-
-typedef struct _EekboardService EekboardService;
-typedef struct _EekboardServiceClass EekboardServiceClass;
-typedef struct _EekboardServicePrivate EekboardServicePrivate;
-
-/**
- * EekboardService:
- *
- * Manages DBus interaction.
- *
- * The #EekboardService structure contains only private data and
- * should only be accessed using the provided API.
- */
-struct _EekboardService {
-    /*< private >*/
-    GObject parent;
-
-    EekboardServicePrivate *priv;
-};
+G_DECLARE_DERIVABLE_TYPE (EekboardService, eekboard_service, EEKBOARD, SERVICE, GObject)
 
 /**
  * EekboardServiceClass: