message: Extend python exception `cv.error`
  to provide `file`, `func`, `line`, `code`, `msg`, and `err` attributes
diff: @@ -110,7 +110,7 @@ PyObject* pyopencv_from(const TYPE& src)
  #include <map>
  -static PyObject* opencv_error = 0;
  +static PyObject* opencv_error = NULL;
  static int failmsg(const char *fmt, ...)
  {
  @@ -171,6 +171,12 @@ try \
  } \
  catch (const cv::Exception &e) \
  { \
  + PyObject_SetAttrString(opencv_error, "file", PyString_FromString(e.file.c_str())); \
  + PyObject_SetAttrString(opencv_error, "func", PyString_FromString(e.func.c_str())); \
  + PyObject_SetAttrString(opencv_error, "line", PyInt_FromLong(e.line)); \
  + PyObject_SetAttrString(opencv_error, "code", PyInt_FromLong(e.code)); \
  + PyObject_SetAttrString(opencv_error, "msg", PyString_FromString(e.msg.c_str())); \
  + PyObject_SetAttrString(opencv_error, "err", PyString_FromString(e.err.c_str())); \
  PyErr_SetString(opencv_error, e.what()); \
  return 0; \
  }
  @@ -2030,7 +2036,15 @@ void initcv2()
  PyDict_SetItemString(d, "__version__", PyString_FromString(CV_VERSION));
  - opencv_error = PyErr_NewException((char*)MODULESTR".error", NULL, NULL);
  + PyObject *opencv_error_dict = PyDict_New();
  + PyDict_SetItemString(opencv_error_dict, "file", Py_None);
  + PyDict_SetItemString(opencv_error_dict, "func", Py_None);
  + PyDict_SetItemString(opencv_error_dict, "line", Py_None);
  + PyDict_SetItemString(opencv_error_dict, "code", Py_None);
  + PyDict_SetItemString(opencv_error_dict, "msg", Py_None);
  + PyDict_SetItemString(opencv_error_dict, "err", Py_None);
  + opencv_error = PyErr_NewException((char*)MODULESTR".error", NULL, opencv_error_dict);
  + Py_DECREF(opencv_error_dict);
  PyDict_SetItemString(d, "error", opencv_error);
  //Registering UMatWrapper python class in cv2 module:
  