In the browse web application, differences between consecutive revisions
(in terms of modified/added/deleted/renamed files) should be available for display.

The algorithm described in that blog post https://blog.sourced.tech/post/difftree/
(with its go implementation https://github.com/src-d/go-git/tree/master/utils/merkletrie) seems
an effective solution to perform that task.

This should be reusable for other contexts but as a first try to implement it,
let's focus on the web browse context.