simplifed the error page
revert dialog traffic-light number no longer hidden
tweaked diff-page controls layout; removed unneeded code from 404/500 pages
tweaked location of diff-page << < > >> controls to free space at top left for (?) help button
made a start at putting (?) help button at top left of dashboard and diff pages (to match test page)
move dashboard tips into tips dialog on front page and removed dashboard tips button
changed default seconds-per-column value to 60
minor html tidy up