Added documentation for sys.maxunicode and sys.warnoptions.

Fixed a markup error which caused an em dash to be presented as a minus sign.
This closes SF bug #458350.

Doc/lib/libsys.tex

@@ -256,10 +256,17 @@ else:
 \begin{datadesc}{maxint}
   The largest positive integer supported by Python's regular integer
   type.  This is at least 2**31-1.  The largest negative integer is
-  \code{-maxint-1} -- the asymmetry results from the use of 2's
+  \code{-maxint-1} --- the asymmetry results from the use of 2's
   complement binary arithmetic.
 \end{datadesc}
 
+\begin{datadesc}{maxunicode}
+  An integer giving the largest supported code point for a Unicode
+  character.  The value of this depends on the configuration option
+  that specifies whether Unicode characters are stored as UCS-2 or
+  UCS-4.
+\end{datadesc}
+
 \begin{datadesc}{modules}
   This is a dictionary that maps module names to modules which have
   already been loaded.  This can be manipulated to force reloading of
@@ -450,6 +457,12 @@ else:
   \versionadded{2.0}
 \end{datadesc}
 
+\begin{datadesc}{warnoptions}
+  This is an implementation detail of the warnings framework; do not
+  modify this value.  Refer to the \refmodule{warnings} module for
+  more information on the warnings framework.
+\end{datadesc}
+
 \begin{datadesc}{winver}
   The version number used to form registry keys on Windows platforms.
   This is stored as string resource 1000 in the Python DLL.  The value