After this commit, we'll need to add validations that it does the
desired work, which we presently know that it doesn't. Given the
changes I made with a plethora of renamings, I want to commit this
now before it gets even larger.
- Kill Close in Persistent and document interface.
- Extract batching behavior into interface.
- Kill IteratorManager, which was used for unknown reasons.
Kill LevelDB watermarks due to redundancy.
General interface documentation has begun.
Creating custom types for the model to prevent errors down the
road.
Renaming of components for easier comprehension.
Exposition of interface in LevelDB.
Slew of simple refactorings.
