This was done with this script:

    #!/bin/bash

    set -eou pipefail

    # Use C++11 sstream constructor from string
    # Exclude 'ThirdParty' because it uses ossimFilename type
    find Modules/ Examples/ -not -iwholename "*ThirdParty*" -type f -print0 | xargs -0 sed -i -E "s/std::ifstream (.*)\((.*)\.c_str\(\)/std::ifstream \1\(\2/"
    find Modules/ Examples/ -not -iwholename "*ThirdParty*" -type f -print0 | xargs -0 sed -i -E "s/std::ofstream (.*)\((.*)\.c_str\(\)/std::ofstream \1\(\2/"

    # Use C++11 ::open(const std::string&) of ifstream, ofstream, etc.
    # Exclude ThirdParty because of ossimFilename type
    find Modules/ Examples/ -not -iwholename "*ThirdParty*" -type f -print0 | xargs -0 sed -i -E "s/\.open\((.*).c_str\(\)/\.open\(\1/"

    # No need for c_str when outputing to std::cout and such
    find Modules/ Examples/ -type f -print0 | xargs -0 sed -i -E "s/\.c_str\(\) ?<</ <</"

    # Use itk::ExceptionObject::SetDescription and SetLocation...