On item edit form open, fade other item listings and add scroll if necessary

[davidmcclure]

Right now, the item edit forms just open up below the item listing and the listing scrolls to the top of the region. This works fine now, since the forms are small and it's rare that they would be taller than the height of the window.

Since it's likely that more options will be added to these forms, though (configuration options for the appearance of the timeline entry, etc.) these forms will probably eventually become tall enough that it's conceivable that they could exceed the height of the items editor block.

This is not a huge problem, since you can always just scroll the whole container div with the items to see more of the form. But, this can be unwieldy if there are lots of items - going down just a little bit can be hard if the total scroll height of the region is really large.

On form open, (a) the other items listings should fade out to emphasize the fact that the edit form is the area of focus, and (b) if the form is higher than the item editor block, the form should only be as tall as the block, and smallscroll() should be added to the form itself so that the form can be scrolled independently of the container.

[davidmcclure]

Moving this to NL enhancements milestone. Something needs to be done about the (now rather quite unwieldy) height of the item edit forms, but it's not at all functionality-critical.

[davidmcclure]

Fixed by expand/contract fieldsets.