alignemnt of the input and resampled images to be adjusted.

Check invalid characters in trees

See merge request fsl/fslpy!121

Also made small fixes to trees that contained invalid characters

Mnt/release prep

See merge request fsl/fslpy!119

Mnt/pre release

See merge request fsl/fslpy!117

Rf/numpy array writeable

See merge request fsl/fslpy!116

winding order, to account for the possibility that different vertex sets
require different orders.

change flag/create a copy themselves

Rf/compressed voxelwise evs

See merge request fsl/fslpy!115

compressed voxelwise EVs

Convert diffusion tensors between 3 formats

See merge request fsl/fslpy!114

- (..., 3, 3) full diffusion tensors
- (..., 6) unique components
- tuple of eigenvectors & eigenvalues

There should be full test coverage of these new functions,
but coverage.py is currently not working for me, so not 100% sure.

Bf/gifti related files

See merge request fsl/fslpy!111

BUG: by default update variables for parent

See merge request fsl/fslpy!109

TEST: Unit test fsl_anat wrapper

See merge request fsl/fslpy!106

Mnt/meta

See merge request fsl/fslpy!108