Enable final cycle specification as an offset.
Feedback changes 1.
Fix bad behaviour for integer cycling with P.
Merge remote branch 'upstream/119.iso8601-cycling' into relative_end_point

Conflicts:
	lib/cylc/config.py
Documented cold vs warm start better.
Enable T06 style final cycles.
Try ... except handling used to handle integer cycling.
Merge pull request #1056 from hjoliver/1043-warm-start-follow-up

1043 warm start follow up
Merge pull request #1055 from arjclark/relative_end_point

#981: final cycle specification as an offset.
Merge pull request #996 from cylc/119.iso8601-cycling

merge "119.iso8601 cycling" to master, for cylc-6
Restructure suite run time log/job/ and work/

Directory structure now looks like:
* `log/job/CYCLE/TASK/{01,02,...,NN}/{job,job.out,job.err,job.status}`
* `work/CYCLE/TASK/`

which should make it easier to archive the log for the whole cycle or to
housekeep all the work files of a given cycle.

`log/job/CYCLE/TASK/NN` is a symbolic link that points to the job log
directory of the latest submit for `TASK.CYCLE`.