- Graphes asynchrones testés en mode prod
- Documentation, README amélioré
- cosmetics: aération du code (en particulier bridgeness...)
- factorisation et meilleur positionnement de la fonction compute_graph

 Modifications qui seront validées :
	modifié :         README.md
	modifié :         bridgeness.py
	modifié :         cooccurrences.py
	modifié :         graph.py

[GRAPH] Now graph as json is saved according to its distance as key (needs to add bridgeness parameter as key).

[FIX] API PUT ngram: new param 'testgroup' can test not only if ngram exists but also if ngram has a mainform

[FIX] new ngram indexing: fix cases where ngram was already partially indexed (ex: if extraction was only correct in some documents) (todo: change bulk_insert_ifnotexists for cases like this)

[GRAPH] Number of nodes need to be saved during the graph generation (and not only with cooc matrix); in order to keep all parameters.

add corpus: reactivate load button for file corpus via minimalist a posteriori validation checks in checkReady function (en attendant mieux :) )