Feature to show PageImages for non-file pages in gallery mode

[VortexArto]

Feature summary (what you would like to be able to do and where): If the PageImages extension is installed, on the Wikimedia DPL, the page image will be used on non-file pages. I thought this feature is also implemented in DPL3, but after testing it out, I guess it's not. I wonder if it's possible for PageImages to be implemented in DPL3.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):

1. Create a dynamic page list using the following parameters:

<DynamicPageList>
category = CategoryName
mode     = gallery
namespace= main
</DynamicPageList>

2. Using the Wikimedia DPL, this would generate a gallery containing the category's pages, with the images being the page-image as defined by the PageImages extension. However, using DPL3, this only generates an empty gallery with a bunch of redlinks (the links being the category's pages, but with "File:" inserted in front of each page title).

Benefits (why should this be implemented?): This would be useful to generate category galleries, with the images being the page image.