[ColinWright]

I've done that, but now got this error:

  const_str.hh: In static member function
                ‘static void const_str::safe_free(const char*)’:
  const_str.hh:33:61: error: ‘free’ was not declared in this scope
    static void safe_free(const char *s) { if (s) free((void*)s); }
                                                               ^

I'd love to get this working - currently running Ubuntu 14.04 LTS, soon to be updated to Ubuntu 18.04 LTS.

Suggestions?