Add DTIPrep extension

See issue #185
Merge pull request #195 from adrienkaiser/update-DTIAtlasBuilder

COMP: Fix windows tests compilation and linking
ENH: DTIProcess packaging system has been simplified
ENH: DTIProcess packaging system has been simplified
ENH: FiberViewerLight packaging system has been simplified
ENH: DTIAtlasFiberAnalyzer now packages on Windows
Merge pull request #197 from booboo69500/update-DTIProcess

ENH: DTIProcess packaging system has been simplified
Merge pull request #199 from booboo69500/update-DTIAtlasFiberAnalyzer

Update dti atlas fiber analyzer
Merge pull request #196 from booboo69500/185-add-DTIPrep

Add DTIPrep extension
Merge pull request #198 from booboo69500/update-FiberViewerLight

Update fiber viewer light
Merge pull request #200 from adrienkaiser/update-DTIAtlasBuilder

COMP: Update FFTW download and install for windows and SlicerExecutionModel version
ENH: DTIPrep now packages on Windows
Merge pull request #201 from booboo69500/update-DTIPrep

ENH: DTIPrep now packages on Windows
Reporting - update version

Consolidating 4.2 and master branch following update of CTK
Merge pull request #202 from fedorov/update-Reporting

Reporting - update version
Fix superbuild in SlicerIGT extension.

Signed-off-by: Tamas Ungi <ungi@cs.queensu.ca>
Merge pull request #205 from ungi/update-SlicerIGT

Fix superbuild in SlicerIGT extension.
ENH: Use find_program to find the paths to the tools to install and update DTI-Reg