Interim login needs some work

[nacin]

A CSS style causes a white 20px stripe at the top of the otherwise gray interim login screen.

That should go, and azaozz thinks the popup should as well.

3.3 for now, but the rest may be punted by azaozz.

In [19124]:

Remove CSS for interim-login. see #19120.

This patch moves the "your session will expire shortly" warning to 2 hours before the cookies expire giving enough time for it to be triggered (no content lost).

The user will be redirected to the login form (with reauth=1) when there's no $_POST data and returned back to the previous screen on logging in, or a warning will be shown on the post edit/write screen by autosave.

It may be too late for this to get in 3.3.