Merge branch 'units' into 'master'

Wiener filter example with units and a little plot routine.

See merge request !59
5 jobs for master in 30 minutes and 49 seconds (queued for 1 second)
Status Name Job ID Coverage
  Test
passed test_min #151784

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passed test_mpi #151785

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passed test_mpi_fftw #151786

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passed test_mpi_fftw_hdf5 #151787

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  Release
passed release_image_master #151788

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