Used by new gifti function relatedFiles

kept in these classes, instead of in FSLeyes.

access. This has been implemented by monkey-patching nibabel.

of (M*3,). New gifti module for basic gifti surface support.

labels - failing when trying to load a label file with no noise components.

voxToWorldMat is changed.

xform. Transform module has new flirtMatrixToSform function which
turns a FLIRT matrix into a src -> struc sform transformation.

returning/assuming transposed affines (column-major). This is because that's
what OpenGL uses.

when it is. New functions in transform module.

EVs

0. AtlasRegistry is no longer thread-safe. It was causing too much
   trouble, and loading atlas descriptions is not a bottle neck anyway,
   so it's completely unnecessary.

1. AtlasDescriptions are now stored as a sorted list.

2. All atlases (including those in $FSLDIR) are saved.

3. More AtlasRegistry methods to rescan, check, and remove atlases.

Little bugfix in Notifier - calling skip/enabled methods with no listeners
registered would result in error.

dimensionality

changed data.