Added a style guide and some suite design sections to the CUG.
A few doc corrections for the previous commit.
More minor doc changes.
Defined HOSTX for new documentation.
Minor style guide text adjustment.
Trim internal line indentation from command scripting.
Updated style guide text based on feedback.
Use splitlines in new trim function.
Fix new trim function.
Typo fix.
cylc performance boosting: reduce bottlenecks
cylc performance boost: implement feedback
cylc performance boosting: tidy and speed up decorator
cylc performance boosting: GUI backwards compatibility
Simplify job poll

The status of job is:
* submitted: job in queueing system, has no status file.
* submission failed: job not in queueing system, has no status file.
* running: job in queueing system, has status file.
* succeeded/failed: job not in queueing system, has status file.
cylc get-job-status: improve test stability

Improve loadleveler tests stability.
Merge branch 'master' into cylc-daemon-performance-rebase
Merge branch 'master' into cylc-daemon-performance-rebase
Merge branch 'master' into cylc-daemon-performance-rebase
cylc output: alter verbosity of some commonly-output messages