Issue #1779026 by dagmar, tim.plunkett, sun, heyrocker: Convert Text Formats to Configuration System.

Issue #1215404 by pillarsdotnet, brianV: Fixed Remove assignment to unused variable $export_data from book_export_html() function.

Issue #1810816 by dawehner, damiankloip, fastangel: Fixed Link options for displayPluginBase is still using the display on the storage.

Issue #1819760 by damiankloip, fastangel, linclark, dawehner: Added a REST export display plugin and serializer integration.

Issue #1831802 by znerol: Fixed Allow implementors of hook_search_admin() to add #submit on the form.

Issue #1788060 by BarisW, swentel: Fixed Translatable string <Hidden> cannot imported if translated.

Issue #1856178 by swentel, sun, ry5n: '#group' Form API property only works with <details> elements.

Merge the Symfony and Drupal route compilers so that we only need to keep track of one.  The Drupal compiler now returns a compiled object that contains all of the Symfony information as well.