Fix :UPDATE and inheritance of @ID and @TYPE slots

src/activity-vocabulary.lisp

@@ -81,10 +81,10 @@ Items of DIRECT-CHILDREN should be of the form,
 ;; https://www.w3.org/ns/activitystreams#Object
 ;; The root of all evil in the world.
 (json-ld::define-json-type (object "Object") () "https://www.w3.org/ns/activitystreams"
-  ((@id
+  ((json-ld:@id
     "id"
     :documentation "Provides the globally unique identifier for an Object.")
-   (@type
+   (json-ld:@type
     "type"
     :documentation "Identifies the Object type. Multiple values may be specified.")
    (attachment

src/json-ld.lisp

@@ -25,6 +25,8 @@
    #:no-@context
    ;; Globals
    #:*default-json-type*
+   ;; Objects
+   #:json-ld-object
    ;; Accessors
    #:json-ld-context #:json-ld-etc #:json-ld-id #:json-ld-type
    ;; Slots
@@ -183,7 +185,7 @@ Here is a brief example partially defining the “Place” type from ActivityStr
                                                't))
                           direct-slots)))
     ;; Save the direct-slots, in case of future :UPDATEs.
-    (setf (gethash (car names) *class-defs*) direct-slots)
+    (setf (gethash (car names) json-ld::*class-defs*) direct-slots)
 
     ;; Now, actually define the class, encoder, etc…
     `(let ((json-class