Core: support to load old project files containing image planes

See forum: https://forum.freecad.org/viewtopic.php?p=670545#p670545

src/App/Application.cpp

@@ -217,6 +217,18 @@ init_freecad_module(void)
     return PyModule_Create(&FreeCADModuleDef);
 }
 
+PyMODINIT_FUNC
+init_image_module()
+{
+    static struct PyModuleDef ImageModuleDef = {
+        PyModuleDef_HEAD_INIT,
+        "Image", "", -1,
+        nullptr,
+        nullptr, nullptr, nullptr, nullptr
+    };
+    return PyModule_Create(&ImageModuleDef);
+}
+
 Application::Application(std::map<std::string,std::string> &mConfig)
   : _mConfig(mConfig), _pActiveDoc(nullptr), _isRestoring(false),_allowPartial(false)
   , _isClosingAll(false), _objCount(-1), _activeTransactionID(0)
@@ -254,6 +266,10 @@ void Application::setupPythonTypes()
     };
     PyObject* pConsoleModule = PyModule_Create(&ConsoleModuleDef);
 
+    // fake Image module
+    PyObject* imageModule = init_image_module();
+    PyDict_SetItemString(modules, "Image", imageModule);
+
     // introducing additional classes
 
     // NOTE: To finish the initialization of our own type objects we must
@@ -2054,7 +2070,7 @@ void Application::initTypes()
     App::DocumentObjectGroup       ::init();
     App::DocumentObjectGroupPython ::init();
     App::DocumentObjectFileIncluded::init();
-    App::ImagePlane                ::init();
+    Image::ImagePlane              ::init();
     App::InventorObject            ::init();
     App::VRMLObject                ::init();
     App::Annotation                ::init();