Requests for comment/Wikidata API

Introduction
This RFC proposes a slightly altered Wikidata API structure to make it more in line with the core API, as well as more feature rich and compact.

The goals of the RFC are
 * Minimalistic results - only retrieve the data that has been asked for, nothing else. This reduces server load, bandwidth costs, and improves speed.
 * Seamless integration - Wikidata extensions should be extending action=query when appropriate. This way all the other features of the query action becomes available, such as combining multiple pieces of information in one query (ask for aliases and what links here together), as well as query continuation.