Start with grouped families in gcylc.

Also removes non-first-parent headings in family-grouped dot view.
Some code reuse.
Merge pull request #468 from hjoliver/gcylc-default-to-grouped

Start with grouped families in gcylc.
Merge branch 'master' into job-poll-and-kill-etc
Commented out a debug print.
Merge branch 'master' into job-poll-and-kill-etc