A significant new system for authentication configuration that

A significant new system for authentication configuration that
exposes the wide array of authentication possibilities.

Authentication now has it's own page separate from other variables.

Most of this work was done by Petri Asikainen <paca@sci.fi>, who started
these changes off.

I've done some cleanups and additions which is why I'm checking it in.

It's all working pretty well at the moment but could use some testing.

Thanks, Petri!  :-)