Update sfmt_nif.c to the latest NIF spec of 17.0

* Remove reload function called from ERL_NIF_INIT

* Remove reloading from functions load() and upgrade()

* Remove all atom containers since they are unused except for 'error_sfmt_nomem'

* Change the behavior of returning atom error_sfmt_nomem to
  just returning enif_make_badarg()

* Remove tabs and replace them by spaces

* Remove trailing whitespaces
Update README.md modification date
Update CHANGES.md to describe NIF return code changes
Merge private development branch of NIF revision