Initial Tortuosity module commit

So far the module is empty.
BUG: Do not build Python extensions when building Slicer modules.

There is an incompatibility between IPython and Slicer's Python.
Merge pull request #332 from thewtex/PythonSlicer

BUG: Do not build Python extensions when building Slicer modules.
Fix scale normalization

The scale normalization would provide the opposite effect than expected.
Change the radius to be spacing*scale instead.
So we have on a 0.05*0.05*0.05 image with a scale of 2.0 a radius of 0.1
instead of 40.

Also remove debug mode on the ridge operator to improve perfomances.
Merge pull request #333 from vovythevov/SegmentTubes-FixScale

Fix scale normalization
Fix SegmentTubes error message
Merge pull request #334 from vovythevov/SegmentTubes-FixScale

Fix SegmentTubes error message
Revert "Fix scale normalization"

This reverts commit 5063c712f9b7b7a877423f16975e502ac72adc42.
The radius normalization was an error, we need the scale to be interpreted
in term of voxel size.
Merge pull request #335 from vovythevov/Revert-SegmentTubes-FixScale

Revert "Fix scale normalization"
ENH: MergeAdjacentImages can now be passed an initial transform
BUG: Fixes transform/inverse for initial bounding box and resampling
Merge pull request #336 from aylward/MergeAdjacentInitTransform

Merge adjacent init transform
BUG: Consistent use of scales in SegmentTubes and new baselines
Merge pull request #337 from aylward/ComputeSegmentTubeParams

BUG: Consistent use of scales in SegmentTubes and new baselines
BUG: Updated MergeAdjacentImagesBaselinesTests
Merge pull request #338 from aylward/MergeAdjacentTests

BUG: Updated MergeAdjacentImagesBaselinesTests
ENH: UseIntensityOnly and other speed to EnhanceTubes and Segmentation
ENH: Choosing optimizer for ridge and radius
Merge pull request #339 from aylward/SpeedSegmentTubes

Speed segment tubes
ENH: SegmentTubes tweaking for speed via stride through mask