Rename and merge all Relation UI code into parent Relation module.
relation_ui.module still exists, which contains some code to generate relations for testing. This has yet to be migrated to Drupal 8.

Relocate relation.views.inc
Cleaned up terminology in relation.views.inc. Left is now source, Right is now target.

naught101 authored May 07, 2013 and dpi committed May 07, 2013

Issue #[1987056] by naught101: Convert line endings to Unix and other coding style.

Removed relation_rules_get_type_options(). Duplicates relation_get_relation_options().
Renamed relation_get_relation_options() to relation_get_relation_types_options().
Renamed relation_get_available_types to relation_get_available_relation_types().
Removed all mentions of relation_get_types(). Replaced with entity_load_multiple().
Removed relation_get_types(), use entity_load_multiple('relation_type').
Removed _relation_get_types_bundles(), see RelationType constructor.
Removed _relation_get_bundle_label(), use entity_get_bundles().
Removed relation_type_ensure_instance(), code moved to RelationType::save()
Removed relation_type_create(), use entity_create()
Removed relation_type_save(), see RelationTypeStorageController::postSave()
Added RelationTypeFormController
Removed relation_ui_type_form() / relation_ui_type_form_submit()
Moved relation type from to RelationTypeFormController.
Added relation_type_uri()
Fixed relation type delete form.

Do not display Relation->(everything) in the Views UI only those relation types that already exist. TODO: what happens to a relation based View?

One Relationship Handler to Rule Them All. (Props to solotandem for the wild idea.) Compare the Views subdir to 5a91a18e.

Provide the scaffolding necessary to get endpoint->relation table->endpoint views relationship handlers.

Revert to Views implementation #1 but using a proper relationship handler. TODO: convert relation table joins to proper handlers, too.

Views integration: setup relation: type as filter_in_operator instead of string #1365406 by dereine.

Replace relationship definitions to cover all the bases and so Relation plays well with Views. #1361780 by solotandem, dereine and chx. Needs followups