message: Import pykeops locally in Silhouette and Lanscapes
diff: # - 2021/11 Vincent Rouvreau: factorize _automatic_sample_range
  import numpy as np
  -from pykeops.numpy import Genred
  from sklearn.base import BaseEstimator, TransformerMixin
  from sklearn.exceptions import NotFittedError
  from sklearn.preprocessing import MinMaxScaler, MaxAbsScaler
  @@ -218,6 +217,7 @@ class Silhouette(BaseEstimator, TransformerMixin):
  self.weight, self.resolution, self.sample_range = weight, resolution, sample_range
  self.im_range = None
  + from pykeops.numpy import Genred
  silhouette_formula = "normalized_weights * ReLU(heights - Abs(x_values - midpoints))"
  variables = [
  "normalized_weights = Vi(1)",
  