Investigate a way to do a partial update in real time

[tbertels]

Currently, a partial (smart) update or full update (on Wednesday) is made every night.

This has two drawbacks:

• The night doesn't happen at the same time in every part of the world, meaning down time or slow down for the rest of the world.
• There's a lag after a user adds or updates wikipedia/wikidata keys, which may lead to confusion.

Proposed solution: Implement if possible a partial update with a queue, updating one element at a time during the whole 24h day instead of everything at once during the night.