Terminate MPI before the end of the main instead of the destructor.
Also clear FFTW threads at the end of DoExecute() not in the destructor.

Add ITK_OVERRIDE msotly in Monteverdi

save override in OTB (need to manually fix this after tidy)
  cd src/Modules ; grep -nR "override" * > ~/temporary/override_otb.txt
  cd ~/software
  python run-clang-tidy.py -checks=-*,modernize-use-override -header-filter=/home/grizonnetm/projets/otb/src/OTB/Modules/.*/.*/include/.* -j8 -fix -p ~/projets/otb/bin/release/OTB-clang3.8/ ~/projets/otb/src/OTB/Modules/*/*/src/*.cxx ~/projets/otb/src/OTB/Examples/*/*.cxx ~/projets/otb/src/OTB/Modules/*/*/test/*.cxx > ~/temporary/run-clang-tidy-log.txt
  #rename override with ITK macro ITK_OVERRIDE
  cd src/Modules
  find . -path ./ThirdParty -prune -o -type f -print -name "*.h" -o -name "*.txx" | xargs perl -pi -e 's/\ override/\ ITK_OVERRIDE/g'

ENH: Modifying extended filename heplers to implement proper checks of options changes in ImageFileReader

This changeset introduce support for Gdal derived subdatasets.

Changes include:
- A new private const method to get the real source name from the derived dataset filename
- An update of the TestFileExistency() method to check for existency of the real source name instead of derived dataset filename
- A patch to make sure OSSIM tries to open the real source name instead of the derived dataset.

If derived datasets are not supported by gdal, ImageFileReader will end with GDALImageIO CanRead saying false, so there should be no impact.