Merge branch 'nifty' into 'master'

Adopt to new nifty version

See merge request !32

test/test_mpi/test_add.py

@@ -5,6 +5,7 @@
 from functools import reduce
 from operator import add
 from types import GeneratorType
+from mpi4py import MPI
 
 import numpy as np
 
@@ -128,5 +129,5 @@ def test_mpi_adder():
         mini_results = []
         for ham in hams_for_sampling:
             with ift.random.Context(42):
-                mini_results.append(mini(ift.SampledKLEnergy(pos, ham, 3, None))[0].position)
+                mini_results.append(mini(ift.SampledKLEnergy(pos, ham, 3, None, comm=MPI.COMM_SELF))[0].position)
         allclose(mini_results)