title: Extract dates from text with spaCy in relation to a given date
body: <p>I want to extract dates, given in text form like <code>'next week'</code> or <code>'February'</code> from a news article, given the date the article was published. I.e. if the article was published on Feb 13 2019 and <code>'next week'</code> was mentioned in that article, I want the function to find Feb 20 2019 for <code>'next week'</code>. Does anybody know how to do that? I was thinking of doing it with spaCy's entity finder and then manually writing a function for every 'DATE' instance, but there must be something better.</p>
  
  <p>Here is my example:</p>
  
  <pre><code>text = """Chancellor Angela Merkel and some of her ministers will
            discuss at a cabinet retreat next week ways to avert driving
            bans in major cities after Germany's top administrative court
            in February allowed local authorities to bar heavily polluting
            diesel cars."""
  article_date = '2019-02-13'
  </code></pre>
  
  <p>My ideal result would be something as the following:</p>
  
  <pre><code> ref_dates = {'next_week': '2019-02-20',
                'february': '2019-02-01'}
  </code></pre>