cylc/cylc#75: first attempt at single updater
cylc/cylc#75: fix led view
cylc/cylc#551: fix trigger in simulation mode
Merge pull request #552 from benfitzpatrick/551.cylc-trigger

#551: fix cylc trigger in simulation mode
update
cylc trigger - fix for duplicate resubmission
Merge pull request #553 from benfitzpatrick/cylc-trigger-fix

cylc trigger - fix for duplicate submission
cylc/cylc#75: debug dot view
Merge pull request #554 from benfitzpatrick/75.single-updater-thread

#75 - single updater thread for the cylc GUI