Python3 support

[rom1sqr]

This project looks dead. But for those wondering how to make a wrapper compatible with Python3,
you just need to replace the PyMODINIT_FUNC init_pydmtx(void) function with this :

static struct PyModuleDef _pydmtx =
{
    PyModuleDef_HEAD_INIT,
    "_pydmtx",
    "",
    -1,
    dmtxMethods
};

PyMODINIT_FUNC PyInit__pydmtx(void)
{
    return PyModule_Create(&_pydmtx);
}

and to remove the init_pydmtx() call in the int main function. That's it!

[msva]

Yeah, project (wrappers) is semi-dead, as all wrappers was made for outdated versions of "backend" languages.

Moreover, for now entire libdtmx project is (at least, temporarily) in maintenance-only mode (so, PRs are welcome)