Merge remote-tracking branch 'janschumann/master' into future

This merge fixes all conflicts but is otherwise untested and might break
funktionality in the auth system somewhere. It NEEDS MAJOR TESTING!

Some refactoring of the auth plugins is still needed:

  * move to PHP5 style
  * fix comments
  * add plugin.info.txt

* janschumann/master:
  Refactored auth system: All auth methods are now introduced as plugins.
  Bugfix: auth types are now correcty added
  Setup auth system from plugins
  Added Auth-Plugin-Prototype to autoload
  Load auth types from plugins in settings_authtype class
  Added prototype for Auth-Plugins
  added plugin type 'auth'

Conflicts:
	inc/auth.php
	inc/auth/pgsql.class.php
	inc/init.php
	inc/load.php
	lib/plugins/auth.php
	lib/plugins/authad/auth.php
	lib/plugins/authldap/auth.php
	lib/plugins/authmysql/auth.php
	lib/plugins/authplain/auth.php