Merge pull request #3 from cylc/master

Pull from origin
Remove quoting remote ssh commands

Quoting the command argument in ssh is unneccessary.

Old behaviour:

    ssh user@host "/path/to/cylc task started"

New behaviour

    ssh user@host /path/to/cylc task started
Updated cat-log command for new task ID delimiter.
Fix styling of families included in node groups.

Closes #363;
Removed use of non-existent graphviz style 'unfilled'.
Added a comment on visualization with MI.
Added graphviz reference URL to the user guide.
Merge pull request #365 from hjoliver/cat-log-task-id-delimiter

Updated cat-log command for new(-ish) task ID delimiter.
Merge pull request #367 from ScottWales/quotes

Remove quotes from remote ssh command
Allow "inherit=None,parent" to make parent secondary.

Addresses #369
Added some verbose validation output.
Merge pull request #370 from hjoliver/369-demote-first-parents

369 demote primary parents with inherit=None,parent
Merge pull request #366 from hjoliver/363-vis-families-in-node-groups

Fix styling of families included in node groups.