to run it:
1) ./manage syncdb
2) add and parse a new corpus
3) test it:
http://localhost:8000/api/corpus/$corpus_id/graph?field1=journal&field2=ngrams
http://localhost:8000/api/corpus/$corpus_id/graph?field1=authors&field2=ngrams

Now, have to update the JSON format for the explorer.

[FEAT] Node_link function now with miam_id and stop_id and (to be tested) group_id. Need to be tested before merge.

	modifié :         functions.py
	Here main changes if needed.

Actions performed:
- remove Trash Nodes
- remove Temporary Lists
- remove Cooc Node

	modifié :         ../templates/corpus/menu.html
	In the menu, url is adapted for each view

	modifié :         ../analysis/functions.py
	function to update current corpus

	modifié :         views.py
	modifié :         corpus_views.py
	corpus views updates (for the url/path mainly)

	modifié :         urls.py
	urls have been added