Fix invalid Python object error

Example below led to a crash:
import Path
v = Path.Tool(name='v', diameter=5.6)
tt = Path.Tooltable()
tt.addTools(v)
attrs = tt.templateAttrs()
uu = Path.Tooltable(tt.templateAttrs())
del attrs

src/Mod/Path/App/TooltablePyImp.cpp

@@ -391,12 +391,18 @@ void TooltablePy::setTools(Py::Dict arg)
             } else {
               PyErr_Clear();
               Path::Tool *tool = new Path::Tool;
-              Path::ToolPy pyTool(tool);
-              if (!pyTool.setFromTemplate(value)) {
-                PyErr_Print();
-                throw Py::Exception("something went wrong");
+              // The 'pyTool' object must be created on the heap otherwise Python
+              // will fail to properly track the reference counts and aborts
+              // in debug mode.
+              Path::ToolPy* pyTool = new Path::ToolPy(tool);
+              PyObject* success = pyTool->setFromTemplate(value);
+              if (!success) {
+                Py_DECREF(pyTool);
+                throw Py::Exception();
               }
               getTooltablePtr()->setTool(*tool, ckey);
+              Py_DECREF(pyTool);
+              Py_DECREF(success);
             }
         } else {
             throw Py::Exception("The dictionary can only contain int:tool pairs");