I should see a manageable subset of Instances

(User Story, Closed -> Fixed, Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )

Summary: This is obvious from the Comics Space, which is very slow to render the root page and the Title Model. We need to be smarter about trimming that back.

Need to think this through, but conceptually we should catch when a Model has more than, eg, 20 Instances, and instead of listing all of them by default, we should render the first 20 and then show a "Show More" link. (Ideally, we should be scroll-smart, but one thing at a time.)

This cut needs to be after sorting. Possibly the Space should maintain a cache of Instances, sorted by their canonical name, to avoid lots of re-sorting?

When you press "Show More", how much gets shown? All of it, or just the next, eg, 100 Instances?

This should apply at least to All Things and to the rendering of Models. Basically, by default we should save users from stupidly long render times.

There should probably be a Number of Instances to Display Property that you can set on Model, which defaults to 20, which is where we get this number from.