Issue #2759461 by DamienMcKenna: hreflang=x-default is no longer removed when another hreflang meta tag has the same URL, instead the other tag is removed as it was supposed to be. Added a new [node:url-original] token for showing the URL for the source node for translations; updated the default value for the hreflang=x-default meta tag to use the new token instead of [node:source:url]. Updates to many tests to allow these changes.
Issue #2654148 by penyaskito, DamienMcKenna: Not all entity.*.add paths are tied to a specific entity form, so don't assume they are; this fixes compatibility with the Lingotek module, possibly others.
Issue #2654148 by bmcclure, DamienMcKenna, agoradesign, miiimooo, JeroenT: Improved support for all entities, exclude certain core entity types, only support ContentEntityType entities that have 'links' defined.