* remove useless clearline call at Interface start
* silence after .handleBreak()
* output '\b' if this.stdout is not a tty (debugger)
* add '\b' checks for clearline (test)

The current behaviour will silently ignore any parsing errors
that may occur when loading a package.json file. This makes
debugging errors in the package.json file very difficult.

This changes the behaviour that that errors opening and reading
the file package.json file continue to be ignored, but errors
in parsing will throw an exception.

* Don't buffer command, before it's execution (repl)
* `quit` command, custom streams for .start, stubbed out test, disable
  history repeation for non-tty (debugger)

[debugger] fix 'debug> connecting...', fixed autostart (XXX figure out why it wasn't working in some cases), fixed highlighting for first line of module's code

micro-refactor, use rli.output.write instead of rli.write ('line' event was emitted for those writes)

Problem was exposed in 12798c62.

Regression from the refactor to move more things into JS.