common auth API for CI

This page is a kind of RFC for building a common API for authentication libraries. Since there is no such core lib, at least we could decide a common interface.

[url=http://codeigniter.com/forums/viewthread/53036/]here is the forum thread[/url]

Quoting benlm, we could start with this structure:

[b]Level 1[/b] would be a library which would have functions like login, logout, register etc. that handle the DB manipulation, sessions, etc. but no views.

[b]Level 2[/b] would have the basic form validation and processing code with defined form parameters and a dead-simple sample view for each (No flash messages, no containers/templates etc.)

[b]Level 3[/b] would have the kitchen sink (views,flash messages, emails sent on password change, etc. with a million configurable parameters.)