Add do_shutdown and simple do_history

Bash is already shut down at exit, but this adds a `do_shutdown` for a restart.  

`do_history`  uses the bash `history` command to fetch the history.  In my tests `do_history` was only called at startup.
At least on my bash, the output from `history` includes line numbers. Also, this isn't a great example, because it ignores all the parameters for limiting and filtering the output.

In fact, I'm starting to think that history requests in the message spec need to be substantially rethought. The only use is a single tail request when the Qt console (& terminal console?) is starting up. So maybe it's best to leave it out of the example until that's worked out.