[h323plus] Security updates to h323plus/GnuGk

To all

No doubt people on the CVS commit list has seen a flurry of commits to both h323plus and GnuGk particularly in the area of security.

H323plus (and GnuGk) now supports H.235.6 with AES256 Media encryption with up to 4096 Diffie-Hellman keys. This mode is compatible with industry standard AES128 with 1048 DH key but provides addition security when calling with h323plus or using GnuGk.

We have also begun adding TLS support to both H323plus and GnuGk to protect signaling. Over the coming weeks we plan to add more features in the H.235.x series.

Simon