Fixes bug #502.

The ownership of the editor returned by the Python override of
QAbstractItemDelegate.createEditor(...) is now transferred to C++.

A test was added to simulate the situation that triggers the bug,
instead of relying on an example with a view, model and editable cells.

See: http://bugs.openbossa.org/show_bug.cgi?id=502

Reviewed by Lauro Moura <lauro.neto@openbossa.org>
Reviewed by Renato Araújo <renato.filho@openbossa.org>

tests/pysidetest/testview.cpp

@@ -1,12 +1,24 @@
 #include "testview.h"
-#include <QDebug>
-#include <stdio.h>
+
+#include <QWidget>
+#include <QAbstractListModel>
+#include <QAbstractItemDelegate>
 
 QVariant
 TestView::getData()
 {
     QModelIndex index;
-    QVariant data = m_model->data(index);
-    return data;
+    return m_model->data(index);
+}
+
+QWidget*
+TestView::getEditorWidgetFromItemDelegate() const
+{
+    if (!m_delegate)
+        return 0;
+
+    QModelIndex index;
+    QStyleOptionViewItem options;
+    return m_delegate->createEditor(0, options, index);
 }