Tmux and Vim: Copy and Paste on macOS Sierra

As a developer, more than anything, you copy and paste things. Making copy and paste work in properly with Vim and Tmux is, unfortunately, not trivial. There’s a lot of information to be found on the internet about setting up copy and paste with Tmux. There’s also lots of information on how to setup Vim. But then you run Vim 8. On macOS Sierra. And things break down quickly.