Issue #2570681 by juanse254, AndreaD, giancarlosotelo, lucastockmann, edurenye: when admin toolbar-oriented vertically a div is over the options

Issue #1363112 by mparker17, mgifford, tlattimore, Jacine, dcmouyard, bowersox, ry5n, ahdiaz: Simplify names of 'element-x' helper classes.

Issue #1987066 by Kevin Morse, JohnAlbin, rteijeiro, echoz, ry5n: Rename files to match CSS file naming convention.

Issue #1971108 by Wim Leers, jessebeach, nod_: Convert contextual.js to use Backbone (and support dynamic contextual links).

Revert "Issue #1971108 by Wim Leers, jessebeach, nod_: Convert contextual.js to use Backbone (and support dynamic contextual links)."

This reverts commit aad2d4a6 since the canges to edit.module were unintended.

Issue #1971108 by Wim Leers, jessebeach, nod_: Convert contextual.js to use Backbone (and support dynamic contextual links).

Issue #849926 by jessebeach, Jacine, mgifford, casey, Mirabuck: Fixed links wrapped in .contextual-links-wrapper divs are not accessible at all via keyboard alone also problems with screen readers.

Issue #1216776 by illmasterc, dawehner, Niklas Fiekas: Fixed Two nested contextual links regions are active, when the outer region is hovered.

Issue #1216978 by cosmicdreams, jyve, mortendk, jessebeach, Jacine, aspilicious: Clean up CSS for Contextual module