Debugger: Tweaks to ConsoleOutputView.

- When receiving console output, we now put it into a pending output list.
  An asynchronous worker thread then tells the view to add another line to
  the output view, with a 10 msec delay between lines. This ensures that if
  the debugged program has a large amount of console output, it doesn't result
  in the debugger UI going unresponsive due to handling the constant influx
  of text insertions in rapid succession.