cv: new formula

A lightweight tool for monitoring the progress of coreutils commands (e.g. a long running `dd`). The difference to other progress viewers like Pipe Viewer or ASCII bar is that the monitor can be launched when the process that should be monitored is already running: https://github.com/BestPig/cv
Oops, I was confused by Github not displaying the end-of-file newlines in the "Normal View".