BUG: MANTIS-1180: Refactored QtWidget wrappers file selection using QtAdapters encapsulated functions.

    Where available, use c++11 features to identify
    potential nullptr usage errors.

    python run-clang-tidy.py -clang-tidy-binary ~/software/clang+llvm-3.8.0-x86_64-linux-gnu-ubuntu-14.04/bin/clang-tidy -checks=-*,modernize-use-nullptr -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/Modules/*/*/app/*.cxx ~/projets/otb/src/OTB/Examples/*/*.cxx ~/projets/otb/src/OTB/Modules/*/*/test/*.cxx > ~/temporary/run-clang-tidy-nullptr-log.txt

    find . -type f -print -name "*.h" -o -name "*.txx" -o -name "*.cxx" |xargs perl -pi -e 's/nullptr/ITK_NULLPTR/g'

BUG: MANTIS-1112 (File not found if filename contains accents when using GUI) Replaced QString::toAscii() by QFile::encodeName() when converting filenames to std::string and used QFile::decodeName() when converting std::string filenames to QString ones.

ENH: OTB-applications wrappers: initialized directory of file-dialog openend when using browse button with edited text.

ENH: Added GetInput() methods to QtWidgetFooParameter classes; Set non-initializerd pointers to NULL on constructor header.

      - Done here to tell to the qt view that the parameter has changed, the view
        ask if the application is ready to be executed, depending on the states of
        parameters, the Execute button is enabled or not