More TODO ideas.
StoreFile interface allows for testability.
Note on bytes.Compare().
Mention SQLite VFS-like feature in README.
Store length twice in root record for earlier offset validation.

This greatly reduces the possibility where storing a gkvlike file root
record as a value in a gkvlite database can cause trouble or
corruption.  The adversary would have to know or guess the size of the
containing gkvlite file for the root record lengths to match.