Issue #742344 by sun, pillarsdotnet, tarmstrong, neilnz, wamilton, lucascaro: Allow forms to set custom validation error messages on required fields.

Issue #1742438 by larowlan, Christian Biggins, kim.pepper, Everett Zufelt: Fixed Vertical tabs header and container rendered even when no vertical tabs.

Issue #1785436 by Boobaa: Fixed Submission of #required elements without #title and empty value does not display any error.

Issue #1414510 by Spleshka, andypost, tim.plunkett: Fixed Remove drupal_reset_static() for drupal_html_id() when form validation fails.

Issue #1496534 by cosmicdreams, alexpott, aspilicious, kim.pepper, acrollet, dagmar, beejeebus, wizonesolutions | heyrocker: Convert account settings to configuration system.

Issue #1739994 by pp, das-peter, Gábor Hojtsy: Use the Language class universally instead of stdObj instances.

Issue #1280996 by tarmstrong, vasi1186, fastangel, dawehner, tobiasb: New language_select() element type for form API.

Issue #1711070 by kid_icarus, tim.plunkett, xjm, droplet, zendoodles and cam8001: Convert tests to use ::$modules property instead of parent::setUp($modules).

Issue #811542 follow-up by David_Rothstein, thekevinday, attiks, quicksketch: Fixed illegal choice errors on radio buttons.

Issue #171267 by tim.plunkett, chx, NROTC_Webmaster: Fixed form redirects remove get variables like sort and order.