MacOS X: Enable 4-way universal builds

This patch adds a new configure argument on OSX:
        --with-universal-archs=[32-bit|64-bit|all]

When used with the --enable-universalsdk option this controls which
CPU architectures are includes in the framework. The default is 32-bit,
meaning i386 and ppc. The most useful alternative is 'all', which includes
all 4 CPU architectures supported by MacOS X (i386, ppc, x86_64 and ppc64).

This includes limited support for the Carbon bindings in 64-bit mode as well,
limited because (a) I haven't done extensive testing and (b) a large portion
of the Carbon API's aren't available in 64-bit mode anyway.

I've also duplicated a feature of Apple's build of python: setting the
environment variable 'ARCHFLAGS' controls the '-arch' flags used for building
extensions using distutils.
diff --git a/Doc/library/macos.rst b/Doc/library/macos.rst
index 832dacb..12ed581 100644
--- a/Doc/library/macos.rst
+++ b/Doc/library/macos.rst
@@ -58,11 +58,19 @@
    elaborate functionality was available), but it provides a convenient location to
    attach a breakpoint in a low-level debugger like :program:`gdb`.
 
+   .. note::
+
+      Not available in 64-bit mode.
+
 
 .. function:: SysBeep()
 
    Ring the bell.
 
+   .. note::
+
+      Not available in 64-bit mode.
+
 
 .. function:: GetTicks()
 
@@ -74,6 +82,10 @@
    Return the file creator and file type as two four-character strings. The *file*
    parameter can be a pathname or an ``FSSpec`` or  ``FSRef`` object.
 
+   .. note::
+      
+      It is not possible to use an ``FSSpec`` in 64-bit mode.
+
 
 .. function:: SetCreatorAndType(file, creator, type)
 
@@ -81,6 +93,9 @@
    ``FSSpec`` or  ``FSRef`` object. *creator* and *type* must be four character
    strings.
 
+   .. note::
+      
+      It is not possible to use an ``FSSpec`` in 64-bit mode.
 
 .. function:: openrf(name [, mode])
 
@@ -98,3 +113,12 @@
    from an application bundle either when it has been started with
    :program:`pythonw` instead of :program:`python` or when running  as an applet.
 
+.. function:: splash([resourceid])
+
+   Opens a splash screen by resource id. Use resourceid ``0`` to close
+   the splash screen.
+
+   .. note::
+
+      Not available in 64-bit mode.
+