Removed the special 'sequential' task type.
Catch exception on rolling_archive.
Merge pull request #828 from arjclark/fix.quota-exceeded-shutdown

#712: Catch exception on rolling_archive.
Implement pre-initial filtering for task messaging.
Added tests for pre-initial cycle messaging.
Document gcylc symlink in cylc-wrapper.
Reimplemented sequential tasks with inter-cycle triggers.
(Re)Documented sequential tasks.
Merge pull request #832 from hjoliver/gcylc-wrapper

Allow "gcylc" for "cylc gui" with the cylc version wrapper.
Merge pull request #831 from arjclark/fix.pre-init-messages

#827: Pre-initial-cycle triggers are now ignored for message outputs
Fixed some test suites.
Fixed a typo.
Minor coding efficiency improvements (credit M.Shin).
Fixed an error in the suicide tutorial suite.
Warn on suiciding an active task.
Log suicides.
Don't retry task message send if task proxy not found in suite.
cylc task messaging: alter send message logging
Merge pull request #837 from hjoliver/suicide-tutorial-typo

Fixed an error in the suicide tutorial suite.
Merge pull request #839 from hjoliver/834.suicide-warning

Log suicides, and warn if task is active at the time