2708. [func] Insecure to secure and NSEC3 parameter changes via

2708.   [func]          Insecure to secure and NSEC3 parameter changes via
                        update are now fully supported and no longer require
                        defines to enable.  We now no longer overload the
                        NSEC3PARAM flag field, nor the NSEC OPT bit at the
                        apex.  Secure to insecure changes are controlled by
                        by the named.conf option 'secure-to-insecure'.

                        Warning: If you had previously enabled support by
                        adding defines at compile time to BIND 9.6 you should
                        ensure that all changes that are in progress have
                        completed prior to upgrading to BIND 9.7.  BIND 9.7
                        is not backwards compatible.