updated docs (online_file, mserver_iface) - the default location of the online_file is /var/run/masqmail/masqmail-route - the online file can and should (!) end with a newline (this once was different) - marked the online detect method `mserver' as obsolete

FILE *peopen(const char *command, const char *type, char *const envp[], int *ret_pid);

FILE *peidopen(const char *command, const char *type, char *const envp[], int *ret_pid, uid_t uid, gid_t gid);