Nothing calls getClassId, so remove it.

lout/identity.hh

@@ -131,14 +131,6 @@ public:
 
    void intoStringBuffer(misc::StringBuffer *sb);
 
-   /**
-    * \brief Returns the class identifier.
-    *
-    * This is rarely used, rather, tests with
-    * identity::IdentifiableObject::instanceOf are done.
-    */
-   std::intptr_t getClassId () { return classId; }
-
    /**
     * \brief Return the name, under which the class of this object was
     *    registered.