extension 'forgets' what it just connected as soon as the url changes

[fuddl]

Steps to reproduce

1. open a thing not yet connected to wikidata and connect it
   
2. immediately after that, open a site, that should be connected to the same wikidata entity (i.e. on imdb open the Cast and Credts section)
   

Expected result

The extension should remember that the thing we have just connected since the website we have open now, also has the same id in its url:

Actual result

The extension has never seen that url before and thus does not know which Wikidata entity is associated to it, and the Wikidata api does not distribute that information yet.

Possible Solution

Add an additional layer of caching that does not only consider the current url but also the extracted id of the current url.

[fuddl]

• switch to a different tab, that can be resolved to an identifier or item and switch back
• close the wd4ff sidebar and open it again
• change to URL in a meaningless way, e.g. adding a parameter not used by the web server and that does not break the regular expression based identifier matching