BUG: FATAL instead of FATAL_ERROR in CMakeLists.txt
BUG: FATAL instead of FATAL_ERROR in CMakeLists.txt

When calling message(FATAL "..."), the configuration process is not
interrupted and one can still generate the project. The key word
that needs to be used in CMake to stop the configuration is
'FATAL_ERROR'.

cdeepakroy/TubeTK,cdeepakroy/TubeTK,KitwareMedical/ITKTubeTK,KitwareMedical/TubeTK,KitwareMedical/ITKTubeTK,sumedhasingla/TubeTK,cdeepakroy/TubeTK,aylward/ITKTubeTK,thewtex/TubeTK,thewtex/TubeTK,aylward/ITKTubeTK,sumedhasingla/TubeTK,KitwareMedical/TubeTK,KitwareMedical/TubeTK,KitwareMedical/TubeTK,sumedhasingla/TubeTK,aylward/ITKTubeTK,sumedhasingla/TubeTK,KitwareMedical/ITKTubeTK,cdeepakroy/TubeTK,thewtex/TubeTK,thewtex/TubeTK,KitwareMedical/ITKTubeTK,aylward/ITKTubeTK