Several interface cleanups.

 - Kill Close in Persistent and document interface.
 - Extract batching behavior into interface.
 - Kill IteratorManager, which was used for unknown reasons.
Include nascent curator scaffolding.

The curator doesn't do anything yet; rather, this is the type
definition including the anciliary testing scaffold.

Improve Makefile and Git developer experience.

The top-level Makefile was a bit overloaded in terms of generation of
assets and their management.  This has been offloaded into separate
Makefiles.

The Git developer experience sucked due to lack of .gitignore
policies.

Also: Fix faulty skiplist naming from old merge.