Identifiers marked as dead due to missing occupation in IMDb

[marfox]

Affects the dead IDs validator check.

Cause: the IMDb people dump seems to have partial occupation lists, and differs from the data displayed on the Web site.

Effects:

• partial population of the appropriate tables in our DB;
• the dead IDs validator check produces lots of false positives just because it looks for something that doesn't exist in our DB, but should.

Example: Q853 is an actor in Wikidata, but nm0001789 is a writer and a director in the IMDb dump: the validator marks Q853 as dead.