We hadn't discussed this, and I thought to reuse the `nrepl-buffer-name-separator' variable. 

It will look like <code>nrepl proj:4009</code> with the project dir enabled, and if the separator variable is used <code>nreplXproj:4009</code>

I thought it would be more consistent to have it look like <code>nrepl proj 4009</code> and <code>nrepl-proj-4009</code>.

Thoughts?