don't require AdminHandler subclasses to specify a model if they specify a form instead
construct AdminHandler instances for each form in an InlinePanel's formset (we aren't using them yet, though)
don't include the script tags in panel JS snippets, because we'll probably want to wrap them in function calls shortly
pass a single 'admin' object to edit views with cleanly-named 'form' and 'panels' properties, none of this 'form_instance' malarkey
have AdminHandler know how to render its own HTML and JS
Wrap the forms of an InlinePanel in their own individual AdminHandlers, and use those for rendering rather than the bog-standard formset renderer; improve panel list auto-generation to cope with forms that have had their fields tinkered with on a per-instance basis, and only include visible fields; add an extra section to the AdminHandler renderer for any fields unaccounted for (such as hidden fields in the above case).
ensure that JS is correctly applied to nested AdminHandler render output, including on elements that are spawned by expandingFormset
ensure that is_valid / pre_save / post_save handlers propagate to child adminhandlers within an InlinePanel