1. Renamed CLASS_VARS() to CLASS_VALUES()
 2. Renamed get_annotations() to get_class_vars()
 3. Renamed has_annotated_property() to has_property_annotations()
 4. Removed 'prefix' => false for all WP_Storage_Base::PROPERTIES()
 5. Changed to using WP_Object_Cache vs. private static properties in WP_Metadata_Base and in one place in WP_Metadata.
 6. Renamed get_defaults() to get_default_args()
 7. Changed default for $property_type from 'string' to 'mixed'
 8. Renamed do_assign_args() to do_process_args()
 9. Renamed $args to $_args and set to null at end of __construct()
 10. Documented a portion of WP_Metadata_Base (the rest comes next)