Part: [skip ci] allow to create empty shapes of each type

src/Mod/Part/App/TopoShapeCompSolidPyImp.cpp

@@ -55,6 +55,13 @@ PyObject *TopoShapeCompSolidPy::PyMake(struct _typeobject *, PyObject *, PyObjec
 
 int TopoShapeCompSolidPy::PyInit(PyObject* args, PyObject* /*kwd*/)
 {
+    if (PyArg_ParseTuple(args, "")) {
+        // Undefined CompSolid
+        getTopoShapePtr()->setShape(TopoDS_CompSolid());
+        return 0;
+    }
+
+    PyErr_Clear();
     PyObject *pcObj;
     if (!PyArg_ParseTuple(args, "O", &pcObj))
         return -1;

src/Mod/Part/App/TopoShapeCompoundPyImp.cpp

@@ -59,6 +59,13 @@ PyObject *TopoShapeCompoundPy::PyMake(struct _typeobject *, PyObject *, PyObject
 // constructor method
 int TopoShapeCompoundPy::PyInit(PyObject* args, PyObject* /*kwd*/)
 {
+    if (PyArg_ParseTuple(args, "")) {
+        // Undefined Compound
+        getTopoShapePtr()->setShape(TopoDS_Compound());
+        return 0;
+    }
+
+    PyErr_Clear();
     PyObject *pcObj;
     if (!PyArg_ParseTuple(args, "O", &pcObj))
         return -1;
@@ -79,7 +86,6 @@ int TopoShapeCompoundPy::PyInit(PyObject* args, PyObject* /*kwd*/)
         }
     }
     catch (Standard_Failure& e) {
-
         PyErr_SetString(PartExceptionOCCError, e.GetMessageString());
         return -1;
     }

src/Mod/Part/App/TopoShapeEdgePyImp.cpp

@@ -121,6 +121,13 @@ PyObject *TopoShapeEdgePy::PyMake(struct _typeobject *, PyObject *, PyObject *)
 // constructor method
 int TopoShapeEdgePy::PyInit(PyObject* args, PyObject* /*kwd*/)
 {
+    if (PyArg_ParseTuple(args, "")) {
+        // Undefined Edge
+        getTopoShapePtr()->setShape(TopoDS_Edge());
+        return 0;
+    }
+
+    PyErr_Clear();
     PyObject *pcObj, *pcObj2;
     double first=DBL_MAX, last=DBL_MAX;
     if (PyArg_ParseTuple(args, "O!|dd", &(Part::GeometryPy::Type), &pcObj, &first, &last)) {

src/Mod/Part/App/TopoShapeFacePyImp.cpp

@@ -117,6 +117,13 @@ PyObject *TopoShapeFacePy::PyMake(struct _typeobject *, PyObject *, PyObject *)
 // constructor method
 int TopoShapeFacePy::PyInit(PyObject* args, PyObject* /*kwd*/)
 {
+    if (PyArg_ParseTuple(args, "")) {
+        // Undefined Face
+        getTopoShapePtr()->setShape(TopoDS_Face());
+        return 0;
+    }
+
+    PyErr_Clear();
     PyObject *pW;
     if (PyArg_ParseTuple(args, "O!", &(Part::TopoShapePy::Type), &pW)) {
         try {

src/Mod/Part/App/TopoShapeShellPyImp.cpp

@@ -77,6 +77,13 @@ PyObject *TopoShapeShellPy::PyMake(struct _typeobject *, PyObject *, PyObject *)
 // constructor method
 int TopoShapeShellPy::PyInit(PyObject* args, PyObject* /*kwd*/)
 {
+    if (PyArg_ParseTuple(args, "")) {
+        // Undefined Shell
+        getTopoShapePtr()->setShape(TopoDS_Shell());
+        return 0;
+    }
+
+    PyErr_Clear();
     PyObject *obj;
     if (!PyArg_ParseTuple(args, "O", &obj))
         return -1;

src/Mod/Part/App/TopoShapeSolidPyImp.cpp

@@ -79,6 +79,13 @@ PyObject *TopoShapeSolidPy::PyMake(struct _typeobject *, PyObject *, PyObject *)
 // constructor method
 int TopoShapeSolidPy::PyInit(PyObject* args, PyObject* /*kwd*/)
 {
+    if (PyArg_ParseTuple(args, "")) {
+        // Undefined Solid
+        getTopoShapePtr()->setShape(TopoDS_Solid());
+        return 0;
+    }
+
+    PyErr_Clear();
     PyObject *obj;
     if (!PyArg_ParseTuple(args, "O!", &(TopoShapePy::Type), &obj))
         return -1;

src/Mod/Part/App/TopoShapeVertexPyImp.cpp

@@ -63,6 +63,13 @@ PyObject *TopoShapeVertexPy::PyMake(struct _typeobject *, PyObject *, PyObject *
 // constructor method
 int TopoShapeVertexPy::PyInit(PyObject* args, PyObject* /*kwd*/)
 {
+    if (PyArg_ParseTuple(args, "")) {
+        // Undefined Vertex
+        getTopoShapePtr()->setShape(TopoDS_Vertex());
+        return 0;
+    }
+
+    PyErr_Clear();
     double x=0.0,y=0.0,z=0.0;
     PyObject *object;
     bool success = false;

src/Mod/Part/App/TopoShapeWirePyImp.cpp

@@ -85,6 +85,13 @@ PyObject *TopoShapeWirePy::PyMake(struct _typeobject *, PyObject *, PyObject *)
 // constructor method
 int TopoShapeWirePy::PyInit(PyObject* args, PyObject* /*kwd*/)
 {
+    if (PyArg_ParseTuple(args, "")) {
+        // Undefined Wire
+        getTopoShapePtr()->setShape(TopoDS_Wire());
+        return 0;
+    }
+
+    PyErr_Clear();
     PyObject *pcObj;
     if (PyArg_ParseTuple(args, "O!", &(Part::TopoShapePy::Type), &pcObj)) {
         BRepBuilderAPI_MakeWire mkWire;