Missing capability to override Walker_Page

[MikeLittle]

Summery: PATCH to add the ability to override Walker_Page and Walker_PageDropdown.

I noticed that unlike the Comment Walker which can be overridden by a user supplied object, there is no way to override the page walker (Walker_Page) or the dropdown page walker (Walker_PageDropdown).

Attached is a patch which adds the ability to supply your own walker objects to both functions.
It uses the same method as for Walker_Comment (a instantiated class supplied to the wp_list_pages() or wp_dropdown_pages() function call.

Note: The method of checking for the added parameters was different for wp_dropdown_pages(), for some reason it does not pass the (fixed) parameters to walk_page_dropdown_tree() unlike those passed to walk_page_tree().

[MikeLittle]

Patch against rev 10226 to implement custom Walker_Page and Walker_PageDropdown

[MikeLittle]

Here is a trivial example of using the new capability.

Add the attachment add-to-functions.php to functions.php in your theme. Add the following calls in your sidebar.

<?php wp_list_pages(array('title_li'=>'<h2>Pages</h2>', 'walker' => new zed1ExamplePageWalker) ); ?>

<?php wp_dropdown_pages(array('title_li'=>'<h2>Pages</h2>', 'walker' => new zed1ExampleDropdownPageWalker) ); ?>

[MikeLittle]

Trivial example of overriding Walker_Page and Walker_PageDropdown

[ryan]

(In [10230]) Allow custom page walker classes. Props MikeLittle. fixes #8673