Added new computation for sigma
changed a comment
new function to compute image noise
added more comments
ENH:
  I added the code that allows for tracking fibers using the mrTrix toolbox.
  The code is added under vistasoft/externals/mrtrix
ENH: Removed file
Merge pull request #6 from frakkopesto/vs_mrtrix

ENH: Added code to call the mrTrix tool box from matlab
some more comments etc
finished bug checking dtiComputeImageNoise
Merge pull request #4 from jyeatman/robust_tensor

Robust tensor
Merge branch 'master' of github.com:vistalab/vistasoft

* 'master' of github.com:vistalab/vistasoft:
  finished bug checking dtiComputeImageNoise
  some more comments etc
  ENH: Removed file
  ENH:   I added the code that allows for tracking fibers using the mrTrix toolbox.   The code is added under vistasoft/externals/mrtrix
  added more comments
  new function to compute image noise
  changed a comment
  Added new computation for sigma