Expose method to Python to get property name of main geometry

fix inheritance of MeshFeaturePy
fix inheritance of PartFeaturePy
remove useless test() method
implement getPyObject in GeoFeature in case a sub-class doesn't implement it

src/App/GeoFeature.cpp

@@ -27,6 +27,7 @@
 #endif
 
 #include "GeoFeature.h"
+#include <App/GeoFeaturePy.h>
 
 using namespace App;
 
@@ -58,3 +59,12 @@ const PropertyComplexGeoData* GeoFeature::getPropertyOfGeometry() const
 {
     return nullptr;
 }
+
+PyObject* GeoFeature::getPyObject(void)
+{
+    if (PythonObject.is(Py::_None())) {
+        // ref counter is set to 1
+        PythonObject = Py::Object(new GeoFeaturePy(this),true);
+    }
+    return Py::new_reference_to(PythonObject);
+}