Feature Request: "Duplicate"

A lot of times when cleaning up branches, I want to duplicate a line, to apply the relevant parts of a commit early, but keep changes to recently-added files where they are. (Things like making an API change at the same time as adding an implementation, I'll duplicate so I can split up "make API change and fix existing impls" from "add new impl which will now land with the new API") This was really easy in Nano, ctrl-k, then press ctrl-u twice (or more), but it's annoyingly hard in this otherwise awesome tool. Sometimes I will use the Insert function but I have to memorize the commit hash to do it that way, because you can't see the todo list when entering your commit hash for I (which is another small UI quirk weakness). Other times I will override the editor to just use Nano again. Wish I had cycles to help contribute this, but at least at the moment I do not. If I get a chance I'll take a look, though. Thanks for this very awesome tool! I joke sometimes that I'm a professional rebaser, and this has made my work a lot easier!