Merge branch 'master' into test_PowerSpace

# Conflicts:
#	nifty/spaces/power_space/power_space.py
4 jobs for test_PowerSpace in 6 minutes and 1 second (queued for 1 minute and 57 seconds)
Name Stage Failure
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test_mpi_fftw Test There is an unknown failure, please try again
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test_mpi_fftw_hdf5 Test There is an unknown failure, please try again
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test_mpi Test There is an unknown failure, please try again
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test_min Test There is an unknown failure, please try again
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