SpecializedListWidgetModule can streamline lists

Inheriting YourListWidgetModule from SpecializedListWidgetModule means
your_list.widget.js.tmpl can define a normal widget literal with
initialize and prepare methods. The prepare method has a
_element (the list) and a _list (the list widget) property that you can use.

This allows us to get rid of ugly constructs like the following:

	jQuery(document).ready(function() {jQuery('table.tag_list').each(function() {jQuery(this).prepareWidget(function(widget) {…