Four small bugs with kar-debugger

[eaepstein]

1. Missing newline when running kar-debugger vb with no breakpoints set.
2. kar-debugger kar invoke command says nothing, does nothing, and hangs if the -app {foo} argument is specified

[eaepstein]

3. A bunch of small ints are dumped when doing "kar invoke".
4. debugger prints msg and hangs when connection to sidecar is broken. Better would be to just exit. Another choice would be to periodically try to reconnect with a short period, and/or try to reconnect on [empty?] command from stdin.