TACACS+ is now in the v4.0.x branch

[Alan DeKok]

  I've just committed a patch to add TACACS+ to the v4.0.x branch:

https://github.com/FreeRADIUS/freeradius-server/commit/6a59647304955d984f2edddca1ccb5828d8c25ee

  It's experimental, and works in basic tests.  Minor things in the configuration are likely to change as we update v4, but the basic TACACS+ functionality should remain the same.

  Thanks to Alexander Clouter for doing the work.  He had to read the TACACS+ proposed standard document, and figure out what it said: not much...

  The implementation is inter-operable with the switches we have access to, but you never now.

  People interested in trying the bleeding edge can now use TACACS+ in the v4 branch.

  Alan DeKok.