[ic] Modify "Promotion" page - add fields

[Russell Mann]

> In IC 5.2, I have a couple of extra fields in my 
> "merchandising" table.  The problem is I can't access them 
> through the UI under "Promotions."  How do I add editable 
> fields to this page?  For the item editor there is a place 
> where you can specify which fields show up, but no such luck 
> for the Promotions editor.
> 
> I see there is a hidden form element called mv_data_fields on 
> this page, but even after picking through Editor.pm I can't 
> figure out how to modify it.

Alright, here's more.  In:

/home/interch/interchange/lib/UI/pages/admin/item_feature.html

There is a test for:

$CGI->{ui_data_fields}

How can I set that variable?

-Russell