Proposed changes to empty command handling in JDB

[Jakob Cornell]

Yeah, `repeat on/off' seems a bit better to me too.  With the command (and the option to use it in a jdbrc) I don't think a command-line option would provide much use, so I'll propose implementing the command alone.

Does this wrap up the pre-CSR discussion?  If so, would you like to see a PR before starting the CSR process or can those two happen concurrently?

Jakob