into the AtlasDescription.labels list.

in the same space as the atlas. This might change in the future.

longer returned by anything - only label values (i.e. volumeindex + 1) and
proportions are returned.

labels than in the description (the striatum ones).

# Conflicts:
#   fsl/version.py

Atlases and resampling

See merge request !36

has no effect when downsampling to a new shape where voxel centres are
aligned.

for us when a new nibabel image is created from an array+existing header

weighted mean correctly.

the former aligns on the centre of voxel (0, 0, 0), whereas the latter aligns
on the corner.

adjusted resample method to force float output (although this might change).

Small API change

See merge request !35