add macro: safe_proc (procedure) and safe_func (function); minor fixes
those macro are safety for pybind11::error_already_set exception. If an error occured, it will print a message by pybind11::print and set result to pybind11::none().
those macro are safety for pybind11::error_already_set exception. If an error occured, it will print a message by pybind11::print and set result to pybind11::none().