Clean up output text

Reported by: markdewing

The output text from QMCPACK needs to be structured better, and only what is useful to an end-user should be shown.

- The output of the ReportEngine is not likely useful to end-users because it requires internal knowledge of the code to make sense. It might be better if this output were disabled by default, and could be enabled with a command line option (either -v, verbose or -d, debug)

- XML fragments - there should be no XML going to stdout