Trace changes in dependencies

[martinthomson]

With Cargo.lock or, failing that, Cargo.toml, there is a record of the effective changes in a crate's dependencies.

Say you had a new dependency, it might be good to identify that as potentially new. But there's not a lot to do with that information other than look at the code for that dependency as a whole.

For an updated dependency, however, being able to navigate to a diff of the changes between the two versions of that dependency would be invaluable.