Don't use SWIG_BUILTIN_INIT for passing SWIG ptrs, use SWIG_POINTER_OWN

* The former is only needed inside tp_init of a new object. Instead when
  we want to pass in and own a pointer, we use SWIG_POINTER_OWN.
* This also removes the need to pass 'self' all the way down in
  ConvertToPy which tidies up a lot of code.

qrenderdoc/Code/pyrenderdoc/qrenderdoc_stub.cpp

@@ -48,7 +48,7 @@ QWidget *PythonContext::QWidgetFromPy(PyObject *widget)
   return NULL;
 }
 
-PyObject *PythonContext::QtObjectToPython(PyObject *self, const char *typeName, QObject *object)
+PyObject *PythonContext::QtObjectToPython(const char *typeName, QObject *object)
 {
   return NULL;
 }