SimObject: add export_method* hooks to export C++ methods to Python

Replace the (broken as of previous changeset) swig_objdecl() method
that allowed/forced you to substitute a whole new C++ struct
definition for SWIG to wrap with a set of export_method* hooks
that let you just declare a set of C++ methods (or other declarations)
that get inserted in the auto-generated struct.

Restore the System get/setMemoryMode methods, and use this mechanism
to specialize SimObject as well, eliminating teh need for sim_object.i.
Needed bits of sim_object.i are moved to the new pyobject.i.
Also sucked a little SimObject specialization into cxx_param_decl()
allowing us to get rid of src/sim/sim_object_params.hh.  Now the
generation and wrapping of the base SimObject param struct is more
in line with how derived objects are handled.

--HG--
rename : src/python/swig/sim_object.i => src/python/swig/pyobject.i

src/python/m5/params.py

@@ -1382,7 +1382,7 @@ class PortRef(object):
 
     # Call C++ to create corresponding port connection between C++ objects
     def ccConnect(self):
-        from m5.internal.params import connectPorts
+        from m5.internal.pyobject import connectPorts
 
         if self.ccConnected: # already done this
             return