RF - rework much of utils
TST - added tests for move_streamlines and affine_for_trackvis
NF - added affine keyword to eudx classes and tests
RF - add affine attribute to markov tracking
RF - rework utils to emphasis affine and deprecate voxel_size
Some work on streamline tools example
RF - make symmetric=True default for connectivity_matrix
Major re-working of the streamline tools example