Convenience namespace to refer to protocol methods and certain internal btree methods
all in one place. See eva.v2.datastructures.bbtree.api for implementation details and docs.

The function of this namespace is to collect the public-facing 'permanent' methods of the
btree code. As new versions are written, the constructors here should be updated to point
to the latest constructor code.

The fressian tags common to all versions -- mostly Clojure Core stuff.

A map-like structure with the following quirks:
- each key is associated with a vector of all values inserted at that key.
- `count' returns the sum of lengths of all vector values.
- it works as a priority-map, sorting each key by the length of its associated vector.
- Corollary: `first' returns the entry with the longest value vector.

Generic get/put-node methods wrapped over the value store protocol.
Non-version-specific. Pointers and Nodes in any version of the btree should
implement the NodeStorageInfo protocol and storage should just work.

Implementation of an append-only immutable vector in secondary storage.
This implementation should behave correctly and safely under concurrent
attempts to read and write. Writing to the end of the vector and reading from
any position in the vector should be O(1). This data structure is intended to
support the immutable write-ahead transaction log backing an Eva database.