Add an interactive command to bounce the REPL

[philc]

Having a command to bounce a REPL would be helpful, since it's a common thing to do during clojure development.

Related: add a command to kill a REPL. Without this, it won't be clear to most users how to kill the underlying JVM that inf-clojure starts -- I don't believe killing the *inf-clojure* buffer does it.

This interactive command (or one of its helper functions) should take as a parameter the buffer who's REPL should be stopped/restarted, for ease of scripting multi-REPL workflows.

[bbatsov]

Just to be clear - "bounce" is the same as "restart" for you, right?

[philc]

That's right.