entity_browser 8.x-1.0-alpha2

Entity browser 8.x-1.0-alpha2
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- Issue #2512702 by slashrsm, Lukas von Blarer, CTaPByK, EclipseGc: Implement configuration UI
- Issue #2667448 by slashrsm, marcingy: Field widget can potentially lose information about selected entities in case of unrelated AJAX requests
- Issue #2666404 by jfrederick: Fix errors on field configuration page.
- Issue #2666914 by slashrsm, marcingy: Notice: Undefined index: shakespeare_messages in entity_browser_preprocess_page__entity_browser__iframe() - line 70
- Issue #2666976 by webflo: Entity Browser Widget populates wrong field.
- Issue #2662610 by rakesh.gectcr, webflo, slashrsm: Add a composer.json file to the module
- Issue #2605578 by CTaPByK, slashrsm: Create selection display plugin that will support multi-step flow.
- Issue #2658688 by slashrsm: Messages are not displayed in iFrame and Modal displays
- Issue #2652658 by slashrsm, snehi, esolitos: Broken field administration page if used Entity Browser is missing
- Issue #2648236 by Berdir: Give iframes a name to facilitate testing
- Issue #2644238 by sanja_m, slashrsm: Improve styling on entity browser field widget
- Issue #2646884 by samuel.mortenson, berdir, slashrsm: Use AJAX for exposed filters, sorts, and pagers.
- Issue #2644688 by Primsi: Duplicated field wrapper markup after selection
- Issue #2644484 by Berdir: Add constant for delete button depth and move displaying the current selection into a separate method.
- Issue #2644000 by Berdir: Add an option to show the details element open by default.
- Issue #2614168 by sanja_m, slashrsm, Berdir: Add "Edit" button on entity reference field widget
- Issue #2635008 by slashrsm, Jose Reyero, jfrederick, Primsi: Convert entity browser form from EntityFormInterface to FormInterface.
- Issue #2631198 by jan.stoeckler, slashrsm: Bug in EntityReference.php / formElement method
- Issue #2634998 by Jose Reyero: Tab and buttons title not translatable
- Issue #2632686 by slashrsm: Chase rename of handlers in Inline entity form.
- Created base class for FieldWidgetDisplay plugins
- Issue #2614092: Only display the field widget options that are usable on the field
- Fix configuration check in entity_form widget
- Issue #2628060 by amateescu: Remove all dependencies on the Entity reference module
- Issue #2628160: Allow percent and other css compatible values
- Issue #2628188: EE Integration: Trigger event after iframe was embedded
- Initialize empty array of entities
- Fix EntityReference widget docs
- Issue #2615148 by sanja_m: Make Drupal.entityBrowser.selectionCompleted default callback for REGISTER_JS_CALLBACKS event