Add absolutePanel and fixedPanel (and jquery-ui)

jQueryUI is needed for draggable functionality.
Smarter cursor choosing for absolutePanel
Minor doc tweak
Merge remote-tracking branch 'origin/master' into feature/absolute-panel

Conflicts:
	DESCRIPTION
Unify jqueryui copies
Merge remote-tracking branch 'jcheng5/feature/absolute-panel'

Conflicts:
	NEWS
	man/validateCssUnit.Rd
Add index entry for absolutePanel