field_group 8.x-3.0-rc1

Important for paragraph users: Make sure you apply the following paragraphs patch: https://www.drupal.org/project/paragraphs/issues/2907094

Changes since 8.x-3.0-beta1:

• #2976425 by timodwhit: View Mode '_custom' should not go through the entity_display_build_alter
• #3033657 by Anicky: Fix deprecated methods
• Temp remove the typehinting
• #3041519 by justin2pin: Fatal error when creating a paragraph
• #3041679 by ameykinalekar: Use mb_* functions instead of deprecated Unicode::* methods
• #3044224 by samuel.seide: Large amount of fields causes tab functionality to break
• #2942075 by Anybody: field_group_theme_suggestions_alter notices
• #3012461 by partdigital, Niklan, mahtab_alam: Horizontal tab content is wrapped by detail border
• #3041207: Syntax error in HorizontalTabs.php causes module installation to fail
• #2768519 by p4trizio, sim_1, zuuperman: Duplicated fields with field_group on referenced ECK entities
• #3022652 by DeFr: Horizontal tabs break keyboard navigation
• #2994995 by Alan-H, larowlan, damondt: Accordion Doesn't Open on Error
• #2904585 by eric.chenchao, sime, gambry, zuuperman: Create field_group.api.php for D8 version
• #2862079 by ckaotik, sime: Choose sensible default tab for horizontal tabs
• #2985485 by stBorchert: Extend signature of field_group_form_process()
• #2977194 by KarenS: Migrated field groups all disabled
• #2986455 by chrisolof: Empty fieldgroups are showing in forms
• #2834055 by cebasqueira: Missing hook_help
• #2824350 by guix, phjou, joachim, NickWilde, Vidushi Mehta: missing UI for description text for field groups
• #2991400 by DuaelFr, zuuperman: Field groups default region should never be null
• Revert "Issue #2991400 by DuaelFr: Field groups default region should never be null"
• #2991400 by DuaelFr: Field groups default region should never be null
• #2945853 by Eallyn, mgerbault: How to create horizontal tabs with 8.x-3.x ?
• #3014125 by dksdev01: XSS patch horizontal-tabs.js
• #2921758 by dpi: Allow modules to define form elements beneath field groups before they are created
• #3001079 by temkin, hswong3i, mahtab_alam: field_group_migrate.info.yml should not contain "version: VERSION"
• 2998205: Fix call to member function errors when the plugin was not found
• #2998205 by nguerrier: PHP message: Error: Call to a member function process() on null
• #3002653 by edysmp: Set default values in migrate destinations plugins
• #3002645 by edysmp: d6 migration doesn't generate the migrations templates
• #2870190 by Simon Georges: Change package name of migrate sub-modules
• #2984756 by cbrody: Accordion/Default State doesn't do anything
• Fix access check for empty groups
• #2948776 by Grimreaper: Fix config schema
• #2941010 by lukus: Markup ID of each tab is not unique
• Revert "Issue #2904577: Duplicate CSS ID confuses behat"
• #2904577: Duplicate CSS ID confuses behat
• #2968184 by jhedstrom: The region part of entity view config isn't set for old installs
• #2960730 by brian.seek: remove extra param in call to field_group_info_groups
• update the processGroup implementations
• #2984382 by szantog: Cannot declare class HtmlElement
• fix extending preRenderGroup
• coding standards
• Remove helpers.inc
• #2949775 by ThomasJacobs: invalid CSS ID for field group causes error
• #2863821 by huzooka, John Pitcairn: Add option to set group label classes for HTML element type
• Fix migration tests
• fix migrate unit test + accordion
• #2951335 by Nebel54, josephgut, rovo, ethomas08, joelpittet, Nchase, ronaldmulero: Getting d6_field_group plugin must define the source_module property Error When Using migrate-upgrade
• #2878359 by zuuperman, DamienMcKenna, DuaelFr, cameronprince, chOP, Alan D.: Field groups are not compatible with field layout
• #2923831 by oknate: Accordion items with children with errors not open
• #2921228 by web247: Accordion doesn't work
• fix syntax errors
• #2958766 by Vidushi Mehta, Ronak.addweb: Convert module to use short array syntax (new coding standard)