Fix Wikidata ID parsing

[larsgw]

Current setup:

1          2           3                4                     5

input ---> array  ---> each element  -> repeat from step 1 -> concat
       \-> string ---> url/single ID -> ID extracted, URL  -> WD JSON
                   \-> Multiple IDs  -> IDs extracted, URL -> WD JSON

Problems:

• difficult to check for test cases (parseInput() on ID should return URL, instead of fetching data from API) [Edit: see Expose parseInput via Cite #34]
• parsing strings with multiple IDs is broken [Edit: fixed in cddab7f]
• strings with single IDs count and are parsed as URLs
• arrays with IDs are taken into another parse loop, which is unnecessarily time-consuming