Consider renaming `OmniBor` type to `OmniBorRecord` or some similar name.

[alilleybrinker]

We probably want to more clearly distinguish between the type that represents a single OmniBOR record (as encoded in a binary or written to a single file) from the full graph representing the associations encoded in a set of OmniBOR records.

If we change OmniBor, we'd also want to change the builder, so we'd have:

• OmniBor → OmniBorRecord
• OmniBorBuilder → OmniBorRecordBuilder

[alilleybrinker]

The old contents of this crate have been entirely dumped, so it makes sense to close this and open new issues to reflect the new work as we need it.