As a developer, I want a simple interface for paginating through some records N at a time

Depends on #22.

Consider the DHT like an unindexed graph database. Once we have structures for sparsely indexing (making discoverable) and iterating over entries, we will develop needs to interact with this shared data in familiar UI patterns.

One such pattern is paginated data- rather than clicking "yesterday" 10 times to locate data 10 days in the past, one should be able to ask for "previous 10 entries" and have them come up if present in the `Path` structure, no matter how many DHT hops it takes to traverse.

Considerations for limiting complexity & network traversals may arise; though most DHT traversals through sparsely sharded `Path` structures should be achievable in linear complexity.