Python fixed many APIs to use const char * instead of char * at around
Python 2.4. As we support 2.7 and later, we can now remove the non-const
string usage.
Types changed:
PyArg_ParseTuple
PyArg_ParseTupleAndKeywords
PyArg_UnpackTuple
PyDict_SetItemString
PyMethodDef
PyModuleDef
SWIG_Python_UnpackTuple
SWIG_Python_str_FromChar
SWIG_addvarlink
swig_const_info
