layout: Keep kind metadata in loaded layouts

It will come useful for applying per-kind styling later without having to give each layout a new stylesheet

eek/eek-xml-layout.h

@@ -31,6 +31,6 @@ G_BEGIN_DECLS
 LevelKeyboard *
 eek_xml_layout_real_create_keyboard (const char *keyboard_type,
                                      EekboardContextService *manager,
-                                     enum layout_type t);
+                                     enum squeek_arrangement_kind t);
 G_END_DECLS
 #endif  /* EEK_XML_LAYOUT_H */