Address large file with dcm2nii _parse_stdout

dcm2nii doesn't print the line _parse_stdout expects when it handles a very large file, which causes large files to be omitted from the output. This fixes that.
remove redundant imports
fix: encode empty lists
Merge pull request #805 from satra/fix/provencode

fix: encode empty lists
Merge pull request #799 from beOn/master

Address large file with dcm2nii _parse_stdout
Merge pull request #803 from mick-d/fsl

Added options to FSL UnaryMaths
Merge pull request #804 from mick-d/camino

Camino
Merge pull request #806 from mick-d/camino

Correction to last PR: name of Camino MESD output
Fixed tracking specs
streamline outputs generation
mandatory cannot be false
Merge pull request #809 from chrisfilo/fix/mrtrix_prob_spec

Important bugfix for MRTrix tracking
Fixed bug in FSL DTIFit interface
Proper list conversion. Closes #811
Added tests
Fix for stop argstr in MRtrix's Streamtrack interface
Updated test for DTIfit
Updated tests for streamtrack-derived interfaces
Merge pull request #812 from swederik/bf/dtifit

Fixed bug in FSL DTIFit interface
Merge pull request #814 from swederik/bf/streamtrack

Fix for stop argstr in MRtrix's Streamtrack interface