Some minor User Guide fixes (typos, line length overruns...).
Some minor User Guide fixes (typos, line length overruns...).
More CUG updates.

Removed some outdated material on "asynchronous tasks"; consistent use of
section references; changed graph "VALIDITY" heading to "RECURRENCE".
Updated some outdated suite.rc ref doc.
Design Principles update.
Added an integer cycling suite.
Merge branch 'cug.cylc-6-final' of github.com:hjoliver/cylc into cug.cylc-6-final

Conflicts:
	doc/cug.tex
Updated CUG suite design principles.
Updated CUG style guide.
Documented integer cycling.
Typo.
Fixed a typo identified in review comments.
Merge pull request #1153 from hjoliver/cug.cylc-6-final

Final changes to the CUG pre cylc-6 release.