(bug 44755) improved tooltip for language terms table in edit mode

* The tooltips displayed when editing values in the language terms table will now display the right
  language from the respective row in the terms table.
* New function, wikibase.getLanguageNameByCode

- minor syntax/doc update

Change-Id: I697a018923817e2c804390cd07ff2f165c8a9e96
Language names in language terms table now links to the entity in that language

Change-Id: I811959b4ef1898ef77a82fa99c845ed9fffa0ebd