Instances listed on the Model page and All Things should sort based on Computed Name

Summary: Currently, if a Model depends on Computed Name, the Instances listed on the Model's page come out unsorted.

This is also true of the list on All Things, which suggests that _sort doesn't take Computed Name into account. Which is unsurprising, but problematic.

See for example the Title page in the Comics Space.

Doing this sort efficiently enough may be an issue. Make sure we only calculate each item's name once.