Hide members of collapsed families properly in graph view.

Also renamed some misleadingly-named variables that dated back to before
we had collapsible families.
Adapt graph to recently changed var names.
Merge branch 'master' into 558.gcylc-hide-fam-members
Merge pull request #568 from hjoliver/558.gcylc-hide-fam-members

Hide members of collapsed families properly in graph view.