Merge pull request #291 from Garyfallidis/fix_buildbot_fail_median_otsu_test

BF: median otsu test was failing at 32 bit buildbots
NF - added affine argument to streamline tools.
TST - added test for affine with streamline_mapping
RF - make coordinate mapping/inversion more clear
BF - fix target function
RF - cleaned up seeds_from_mask and added affine argument
NF - added include argument to target function
DOC - first draft of streamline tools tutorial
DOCS - make streamline_tools render properly as html
NF - added fetcher and reader for stanford labels data
TST - added tests for data fetcher
DOCS - improvements to streamline_tools example
RF - move streamline_mapping to vox2track
RF - import python and cython code into one utils module
RF - rework much of utils
TST - added tests for move_streamlines and affine_for_trackvis
NF - added affine keyword to eudx classes and tests
NF - 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