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.
A poll-and-wait option for stop command.

Closes #300.
Consistent help for the suite-state and stop commands.
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.
Use a common polling framework for the suite-state and stop commands.
Connect only once for suite stop polling.
Fix automatic retrieval of remote suite port numbers.

This closes #330.  The bug was probably introduced recently(ish)
with site/user config files.
Improved error messages for remote suite not running.
Less verbose polling output, on a single line.
Catch connection failed in suite-connecting commands.

This occurs if you try to connect to a suite that is not running but
which has a port number associated with it - either because you used
--port on the command line or because of an orphaned port file.
Fixed indentation error.
Whitespace tidy
Tidying up
Merge pull request #374 from arjclark/cylc-hostname-bugfix

cylc suite db hostname bugfix