Add nested scopes spec to appendix.

Add new opcodes LOAD_CLOSURE, LOAD_DEREF, STORE_DEREF, MAKE_CLOSURE to
docs for dis module.

Add docs for new function and code members in Sec. 3 of ref manual.
They're present regardless of whether nested scopes are used.

Remove description of default argument hack from Sec. 7 of the ref
manual and refer the reader to the appendix.

Doc/lib/libdis.tex

@@ -556,6 +556,25 @@ Stores TOS into the local \code{co_varnames[\var{var_num}]}.
 Deletes local \code{co_varnames[\var{var_num}]}.
 \end{opcodedesc}
 
+\begin{opcodedesc}{LOAD_CLOSURE}{i}
+Pushes a reference to the cell contained in slot \var{i} of the
+cell and free variable storage.  The name of the variable is 
+\code{co_cellvars[\var{i}]} if \var{i} is less than the length of
+\var{co_cellvars}.  Otherwise it is 
+\code{co_freevars[\var{i} - len(co_cellvars)]}.
+\end{opcodedesc}
+
+\begin{opcodedesc}{LOAD_DEREF}{i}
+Loads the cell contained in slot \var{i} of the cell and free variable
+storage.  Pushes a reference to the object the cell contains on the
+stack. 
+\end{opcodedesc}
+
+\begin{opcodedesc}{STORE_DEREF}{i}
+Stores TOS into the cell contained in slot \var{i} of the cell and
+free variable storage.
+\end{opcodedesc}
+
 \begin{opcodedesc}{SET_LINENO}{lineno}
 Sets the current line number to \var{lineno}.
 \end{opcodedesc}
@@ -583,6 +602,14 @@ with the function.  The function object is defined to have \var{argc}
 default parameters, which are found below TOS.
 \end{opcodedesc}
 
+\begin{opcodedesc}{MAKE_CLOSURE}{argc}
+Creates a new function object, sets its \var{func_closure} slot, and
+pushes it on the stack.  TOS is the code associated with the function.
+If the code object has N free variables, the next N items on the stack
+are the cells for these variables.  The function also has \var{argc}
+default parameters, where are found before the cells.
+\end{opcodedesc}
+
 \begin{opcodedesc}{BUILD_SLICE}{argc}
 Pushes a slice object on the stack.  \var{argc} must be 2 or 3.  If it
 is 2, \code{slice(TOS1, TOS)} is pushed; if it is 3,