add Function.js, some updates in OxJS

source/Ox/js/Function.js

@@ -0,0 +1,29 @@
+/*@
+Ox.cache <f> Memoize a function
+    <script>
+        var f = Ox.cache(function(n) { return n * Math.random(); });
+    </script>
+    > f(10) == f(10);
+    true
+    > f(10) == f.clear()(10);
+    false
+@*/
+Ox.cache = function(fn) {
+    var cache = {},
+        ret = function() {
+            var key = JSON.stringify(Ox.makeArray(arguments));
+            return key in cache ? cache[key]
+                : (cache[key] = fn.apply(this, arguments));
+        };
+    ret.clear = function() {
+        if (arguments.length == 0) {
+            cache = {};
+        } else {
+            Ox.toArray(arguments).forEach(function(key) {
+                delete cache[key];
+            });
+        }
+        return ret;
+    }
+    return ret;
+};