Updated the change log for 5.4.0
Update graph string interp doc.
Updated User Guide on inter-cycle triggers at start-up.
Updated User Guide on warm starts.
Merge branch 'master' into release-prep-5.4
Documented triggering off tasks in other suites (by polling).

Also updated the User Guide for the recent REGDB changes.
Updated the change log for 5.4.0.
Fixed a doc typo.
Fixed another doc typo.
Merge branch 'master' into release-prep-5.4
Change log updated.
Merge pull request #731 from hjoliver/release-prep-5.4

Release prep 5.4