BUG: #1757: move siftfast to a subfolder

...es/Feature/Descriptors/include/otbSiftFastImageFilter.hxx

Modules/ThirdParty/SiftFast/src/CMakeLists.txt

Modules/ThirdParty/SiftFast/src/otbsiftfast/AUTHORS

Modules/ThirdParty/SiftFast/src/otbsiftfast/FindBoost.cmake

Modules/ThirdParty/SiftFast/src/otbsiftfast/FindOctave.cmake

Modules/ThirdParty/SiftFast/src/otbsiftfast/INSTALL

Modules/ThirdParty/SiftFast/src/otbsiftfast/LICENSE

...les/ThirdParty/SiftFast/src/otbsiftfast/Makefile-upstream

Modules/ThirdParty/SiftFast/src/otbsiftfast/README

...rdParty/SiftFast/src/otbsiftfast/cmake_uninstall.cmake.in

Modules/ThirdParty/SiftFast/src/otbsiftfast/libsiftfast.cpp

Modules/ThirdParty/SiftFast/src/otbsiftfast/makerelease.sh

Modules/ThirdParty/SiftFast/src/otbsiftfast/profiler.cpp

Modules/ThirdParty/SiftFast/src/otbsiftfast/profiler.h

Modules/ThirdParty/SiftFast/src/otbsiftfast/runcmake.bat

Modules/ThirdParty/SiftFast/src/otbsiftfast/siftfast.cpp

Modules/ThirdParty/SiftFast/src/otbsiftfast/siftfast.h

Modules/ThirdParty/SiftFast/src/otbsiftfast/siftfast.m

Modules/ThirdParty/SiftFast/src/otbsiftfast/siftfastpy.cpp

Modules/ThirdParty/SiftFast/src/otbsiftfast/siftmex.cpp