Fix broken stuff

[cfirmly]

Minimal modifications to get the package on the track

MAINT: assets/__ init __.py

• files are independent from the another package

MAINT: soyclustering/_keyword.py

• correct possible zerodivisionerror

MAINT: soyclustering/_kmeans.py

• "np.int" is deprecated
• "np.matrix" isn't allowed by "sklearn.preprocessing.normalize", calling it raises "TypeError: np.matrix is not supported. Please convert to a numpy array with np.asarray."