Graph and gcylc collapsing: start with vis settings

if defined, otherwise default to initially all collapsed.
Adjust graph command source for previous commit.

Initial collapsed node structure is now handled internally, for graph
command and gcylc graph view.
Updated documentation.
Fix previous change.

The 'group_nodes' list in get_graph_raw() is supposed to hold nodes to
be grouped into their parent nodes (usually from the right-click Group
option), not for the parent nodes themselves.
Merge branch 'master' into gui-collapsed-families

Conflicts:
	lib/cylc/config.py
Replace another doublecircle with tripleoctagon.
Hot fix for gcylc with no suite arg.
Merge pull request #565 from hjoliver/gui-collapsed-families

Repect "[visualization]collapsed families" config item.
Add suite connection messages.
Removed some debug.
Host scan list should be taken from combined global config.

It was being taken specifically from site config, which would ignore any
user override in the cylc user config file.
Merge pull request #572 from arjclark/cylc-suite-state-verbose

cylc suite state: verbose mode
Merge pull request #573 from hjoliver/gsummary-host-list-config

gsummary - Host scan list should be taken from combined global config.
Removed some obsolete code.

(was associated with the old task elimination algorithm)
Removed associated documentation comments and syntax strings.
Merge pull request #574 from hjoliver/remove-obsolete-task-elimination-code

Removed some obsolete code

Removed code associated with `use quick task elimination`.