BGE Python API

This changes how the BGE classes and Python work together, which hasnt changed since blender went opensource.
The main difference is PyObjectPlus - the base class for most game engine classes, no longer inherit from PyObject, and cannot be cast to a PyObject.

This has the advantage that the BGE does not have to keep 2 reference counts valid for C++ and Python.

Previously C++ classes would never be freed while python held a reference, however this reference could be problematic eg: a GameObject that isnt in a scene anymore should not be used by python, doing so could even crash blender in some cases.

Instead PyObjectPlus has a member "PyObject *m_proxy" which is lazily initialized when python needs it. m_proxy reference counts are managed by python, though it should never be freed while the C++ class exists since it holds a reference to avoid making and freeing it all the time.
When the C++ class is free'd it sets the m_proxy reference to NULL, If python accesses this variable it will raise a RuntimeError, (check the isValid attribute to see if its valid without raising an error).
- This replaces the m_zombie bool and IsZombie() tests added recently.

In python return values that used to be..
 return value->AddRef();
Are now
 return value->GetProxy();
or...
 return value->NewProxy(true); // true means python owns this C++ value which will be deleted when the PyObject is freed

source/gameengine/Ketsji/KX_PythonInit.cpp

@@ -359,8 +359,7 @@ static STR_String gPyGetCurrentScene_doc =
 "Gets a reference to the current scene.\n";
 static PyObject* gPyGetCurrentScene(PyObject* self)
 {
-	Py_INCREF(gp_KetsjiScene);
-	return (PyObject*) gp_KetsjiScene;
+	return gp_KetsjiScene->GetProxy();
 }
 
 static STR_String gPyGetSceneList_doc =  
@@ -369,7 +368,6 @@ static STR_String gPyGetSceneList_doc =
 static PyObject* gPyGetSceneList(PyObject* self)
 {
 	KX_KetsjiEngine* m_engine = KX_GetActiveEngine();
-	//CListValue* list = new CListValue();
 	PyObject* list;
 	KX_SceneList* scenes = m_engine->CurrentScenes();
 	int numScenes = scenes->size();
@@ -380,13 +378,10 @@ static PyObject* gPyGetSceneList(PyObject* self)
 	for (i=0;i<numScenes;i++)
 	{
 		KX_Scene* scene = scenes->at(i);
-		//list->Add(scene);
-		PyList_SET_ITEM(list, i, scene);
-		Py_INCREF(scene);
-		
+		PyList_SET_ITEM(list, i, scene->GetProxy());
 	}
 	
-	return (PyObject*)list;
+	return list;
 }
 
 static PyObject *pyPrintExt(PyObject *,PyObject *,PyObject *)