dtifit --kurtdir does not produce mean kurtosis maps anymore

there are sevaral definitions of MK, most of which are not compatible with the simplified kurtosis model implemented by --kurtdir. So, I decided not to compute anything at all.

unit_tests/fdt/dtifit/feedsRun

@@ -229,7 +229,6 @@ for directory, multi_shell, kurt in gen_data():
             if fkurtdir:
                 for idx, ref in zip(range(1, 4), [0.1, 0.05, 0.2]):
                     fit = nib.load(f'{base_output}_kurt{idx}.nii.gz').get_fdata()
-                    #print('kurtosis', idx, ref, fit[0, 0, 0])
                     if kurt == 0:
                         testing.assert_allclose(fit, 0., atol=1e-5)
                     elif kurt == 1:
@@ -237,19 +236,10 @@ for directory, multi_shell, kurt in gen_data():
                     elif kurt == 2:
                         testing.assert_allclose(fit, ref, rtol=0.1)
 
-                MK = nib.load(f'{base_output}_MK.nii.gz').get_fdata()
-                if kurt == 0:
-                    testing.assert_allclose(kurt, 0., atol=1e-5)
-                elif kurt == 1:
-                    # k_para and k_perp = 1 is different from MK=1...
-                    assert not np.allclose(MK, 0.1, rtol=0.01)
-                elif kurt == 2:
-                    testing.assert_allclose(MK, 0.35 / 3, rtol=0.1)
             else:
                 assert not os.path.isfile(f'{base_output}_kurt1.nii.gz')
                 assert not os.path.isfile(f'{base_output}_kurt2.nii.gz')
                 assert not os.path.isfile(f'{base_output}_kurt3.nii.gz')
-                assert not os.path.isfile(f'{base_output}_MK.nii.gz')
         else:
             if isinstance(base_output, CalledProcessError):  # dtifit crashed
                 print("dtifit crashed on an invalid run, which is fine")