NewFootnotes creates and returns a new `Footnotes` instance.

NewGraph creates and returns a new `*Graph` instance.

ScanRepositoryUsingGraph scans `repo`, using `rg` to decide which references to scan and how to group them.

Footnotes collects and numbers footnotes for a `table`.

Graph is an object graph that is being built up.

Structure for keeping track of an object whose path we want to know (e.g., the biggest blob, or a tree containing the biggest blob, or a commit whose tree contains the biggest blob).

RefGroup is a group of references, for example "branches" or "tags".

PathResolver figures out a "reachability path" (i.e., Git `rev-parse` input, including commit and/or file path) by which specified objects are reachable.

RefGrouper describes a type that can collate reference names into groups and decide which ones to walk.

RefGroupSymbol is the string "identifier" that is used to refer to a refgroup, for example in the gitconfig.