RF: Generalize Wrotate_element to accept arrays of voxels instead of single voxels. Remove voxel looping in functions that call Wrotate_element, as mean_kurtosis and radial_kurtosis. Functions are now less computationally demanding. Change function's documentation according to changes
RF: Generalize Wrotate_element to accept arrays of voxels instead of single voxels. Remove voxel looping in functions that call Wrotate_element, as mean_kurtosis and radial_kurtosis. Functions are now less computationally demanding. Change function's documentation according to changes

matthieudumont/dipy,FrancoisRheaultUS/dipy,villalonreina/dipy,JohnGriffiths/dipy,nilgoyyou/dipy,demianw/dipy,JohnGriffiths/dipy,nilgoyyou/dipy,matthieudumont/dipy,StongeEtienne/dipy,FrancoisRheaultUS/dipy,villalonreina/dipy,StongeEtienne/dipy,demianw/dipy