Add OpenIdTextBox.UsePopup property

[http://blog.nerdbank.net/]

The UsePopup property should be an enum with these values:

public enum PopupOptions {

Never,
Always,
IfProviderSupported,

}

In all cases the popup should comply with the UI extension guidelines including size, positioning, location bar, and the dimming out of the RP page, and responding to the window.onclosed event.

[http://david.christiansen.myopenid.com/]

So, we will need to bring a level of Ajax-ness to the textbox to ascertain whether the OP is capable of supporting PopUp? UI.

[http://blog.nerdbank.net/]

master 674cc8db0