Assigned category selection now AJAX-powered

The categoryi module now supports activeselect-powered AJAX for category selection forms! This is extremely cool - definitely one of the coolest user interface enhancements that Drupal has ever had. The way it works is as follows: if you have two containeris on (for example) your site's 'add story' form, and the categories in one container (e.g. 'cities') have categories in another container (e.g. 'countries') as their distant parentiis, then the two select boxes will be linked by AJAX! Select a different country, and the list of cities will change on-the-fly.

What's even more cool is that this linking can work recursively. So you can have as many levels of distant parents as you want - for example, you can have 'countries', 'cities', 'suburbs', and 'streets' - and when you change the selected country, all three other select boxes will suddenly change!

As with the previous AJAX enhancement to the category module, this enhancement requires the activeselect module, and it degrades gracefully if that module is not installed (or if the user's browser does not have adequate JS support). Also, the recursive / cascading activeselect feature is still buggy in IE6 - if you want to play around with it, you'll have to do so in a real browser (for now), such as Firefox. Update: the IE6 AJAX bug has now been fixed.