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`.