Fix some cleanup issues. Better error pages for bad dactyl: URLs. Remove some dead code. Other cleanup.

common/modules/base.jsm

@@ -851,7 +851,7 @@ Class.extend = function extend(subclass, superclass, overrides) {
  *      property's value.
  * @returns {Class.Property}
  */
-Class.memoize = function memoize(getter, wait)
+Class.Memoize = Class.memoize = function Memoize(getter, wait)
     Class.Property({
         configurable: true,
         enumerable: true,
@@ -893,6 +893,19 @@ Class.memoize = function memoize(getter, wait)
         }
     });
 
+/**
+ * Updates the given object with the object in the target class's
+ * prototype.
+ */
+Class.Update = function Update(obj)
+    Class.Property({
+        configurable: true,
+        enumerable: true,
+        init: function (key, target) {
+            this.value = update({}, target[key], obj);
+        }
+    });
+
 Class.replaceProperty = function replaceProperty(obj, prop, value) {
     Object.defineProperty(obj, prop, { configurable: true, enumerable: true, value: value, writable: true });
     return value;