Add Object.same(_,_) to access built-in equality even for classes that may override ==.

Had to add a new metaclass for Object since it now has its own static method so we
can't just use Class as its metaclass. (We don't want *every* class to have a same(_,_)
static method.)

doc/site/core/object.markdown

@@ -1,6 +1,21 @@
 ^title Object Class
 ^category core
 
+## Static Methods
+
+## **same**(obj1, obj2)
+
+Returns `true` if *obj1* and *obj2* are the same. For [value
+types](../values.html), this returns `true` if the objects have equivalent
+state. In other words, numbers, strings, booleans, and ranges compare by value.
+
+For all other objects, this returns `true` only if *obj1* and *obj2* refer to
+the exact same object in memory.
+
+This is similar to the built in `==` operator in Object except that this cannot
+be overriden. It allows you to reliably access the built-in equality semantics
+even on user-defined classes.
+
 ## Methods
 
 ### **!** operator
@@ -9,9 +24,9 @@ Returns `false`, since most objects are considered [true](control-flow.html#trut
 
 ### **==**(other) and **!=**(other) operators
 
-Compares two objects using built-in equality. This compares numbers by value,
-and all other objects are compared by identity—two objects are equal only
-if they are the exact same object.
+Compares two objects using built-in equality. This compares [value
+types](../values.html) by value, and all other objects are compared by
+identity—two objects are equal only if they are the exact same object.
 
 ### **toString**