removed old ugly fix in streamline2rgb since now we require rencent DiPy
removed old commented-out code explaining a previous change
removed old commented-out code for computing buffers
improved docstring
removed qb wrapper since data are not downsampled anymore
improved docstring
removed qb unused code
removed commented-out unused code and empty lines
removed commented-out old code
removed commented-out old code + comment to mark potentially useless code
removed commented-out old code about qb
removed commented-out old unused code from previous versions