Issue #2878548 by alexpott, droplet, Cottser, idebr, joelpittet, xjm, martin107: Fix CSS whitespace issues

Issue #2408511 by joaogarin, pjbaert, rpayanm, bobrov1989: Rewrite vertical-tabs component inline with our CSS standards

Issue #2015789 by fubhy, echoz, rteijeiro, LewisNyman, penyaskito: Remove language_css_alter() (RTL stylesheets) in favor of HTML 'dir' attribute.

Issue #1168246 by sun, mgifford, Manuel Garcia, mbrett5062, ry5n, Everett Zufelt, nod_, aspilicious, deviantintegral, tim.plunkett: Freedom For Fieldsets! Long Live The DETAILS.

Issue #1015798 by Mohammed J. Razem, xjm, drunken monkey: Fixed Fieldsets inside vertical tabs have no title and can't be collapsed.

Nate Lampton authored Oct 30, 2011 and catch committed Nov 01, 2011

Issue #22336 by quicksketch, scor, boombatower, and rfay. Move all core Drupal files under a core subdirectory.

#925350 by reglogge, Jacine, Jeff Burnz: Fixed Vertical tabs markup to restore RTL support and fix other bugs.

#467296 by Frank Ralf, mgifford, Everett Zufelt, Cliff,seutje, Bojhan, kat3_drx, et al: Accessibility improvements for vertical tabs.

#474242 by tic2000: Use more specific CSS selectors for Vertical Tabs to prevent breakage by other modules.

#473878 by tic2000: Fix vertical tabs styling which was accidentally mangled in content-region-as-a-block patch.

#323112 follow-up by kkaefer: Make tab titles enclosed in <strong> tags to indicate importance from surrounding text.

#323112 by dmitrig01, kkaefer, quicksketch, frando and many many more: Now presenting... Vertical Tabs. Fantastic new UI improvement for node forms and hopefully more in the future.