Mulit-widget widget addition broken with JS turned off.

[mdawaffe]

Another problem caused by our code's lack of differentiation between a type of widget and an instance of that type.

There may not be a perfect fix for this. I'm looking into it.

[mdawaffe]

With the current code, it is essentially impossible to add a multi-widget instance without going through a POST request.

For non-JS users, the attached patch inserts an intermediate page load between clicking "Add" on a multi-widget and seeing the new instance of that multi-widget showing up in the "Current Widgets" list. This intermediate page lets the user fill out the form fields for that instance of the multi-widget and lets WP process a POST request.

Attached also:

1. Cleans up a potential PHP warning.
2. Makes it possible for non-JS users to edit the first widget in the "Current Widgets" list.
3. Makes it possible for non-JS users to remove widgets from the "Current Widgets" list.
4. Adds nonce check to widget's "Save Changes" POST request (oops!).

[ryan]

(In [7362]) Fix multi-widget addition with JS disabled. Props mdawaffe. see #6239

[mdawaffe]

No complaints. FIXED.