text: Title: Add support for a `sort` argument in WordNet methods
  Body: WordNet object methods support a series of methods, such as `hypernyms`, `antonyms`, etc., that under the hood use a private method called `_related`, that supports an argument called `sort` which by default is `True`. This argument sorts the output objects by name. For example, see:
  
  https://github.com/nltk/nltk/blob/e2d368e00ef806121aaa39f6e5f90d9f8243631b/nltk/corpus/reader/wordnet.py#L134-L135
  
  However, in some cases, we don't need the output to be sorted, and we may be performing these operations multiple times and on long lists, which incurs in considerable penalties because of multiple needless sorting going on under the hood.
  
  Thus, I believe it'd be important that such methods supported a `sort` argument (as `_related` does), whose default value is `True` (to avoid breaking backward compatibility).