message: core/CMake: Minor improvements
  Moved generation of Version.hpp file behind FFT decisions, since the user settings can still be changed, depending on the available libs etc.
  Added an additional warning message if kissFFT is used together with OpenMP
diff: @@ -176,7 +176,6 @@ if( SPIRIT_USE_THREADS )
  set( THREAD_LIBS Threads::Threads )
  endif()
  configure_file( ${CMAKE_CURRENT_LIST_DIR}/CMake/Spirit_Defines.h.in ${CMAKE_CURRENT_LIST_DIR}/include/Spirit_Defines.h )
  -configure_file( ${CMAKE_CURRENT_LIST_DIR}/CMake/Spirit_Version.hpp.in ${CMAKE_CURRENT_LIST_DIR}/include/utility/Version.hpp )
  ####################################################################
  @@ -194,6 +193,7 @@ if( SPIRIT_USE_OPENMP )
  message( STATUS ">> OpenMP EXE Linker Flags: ${OpenMP_EXE_LINKER_FLAGS}" )
  else( OPENMP_FOUND )
  message( WARNING ">> OpenMP could not be found." )
  + set(SPIRIT_USE_OPENMP OFF)
  endif( OPENMP_FOUND )
  endif()
  ####################################################################
  @@ -247,11 +247,16 @@ if( NOT SPIRIT_USE_CUDA AND NOT FFT_LIB )
  message( STATUS ">> Using FFTW" )
  set( FFT_INCLUDE_DIRS ${FFTW_INCLUDES} )
  set( SPIRIT_COMPILE_DEFINITIONS ${SPIRIT_COMPILE_DEFINITIONS} -DSPIRIT_USE_FFTW )
  + else()
  + set(SPIRIT_USE_FFTW OFF)
  endif()
  endif()
  if( (NOT SPIRIT_USE_FFTW) OR (NOT FFTW_FOUND) )
  message( STATUS ">> Using kissFFT" )
  + if( SPIRIT_USE_OPENMP )
  + message( WARNING "Using kissFFT together with OpenMP. If you intend to perform calculations including dipole-dipole interactions with OpenMP it is *strongly* recommended to use FFTW instead!" )
  + endif()
  add_definitions( -Dkiss_fft_scalar=${SPIRIT_SCALAR_TYPE} )
  set( SPIRIT_COMPILE_DEFINITIONS ${SPIRIT_COMPILE_DEFINITIONS} -DSPIRIT_USE_KISSFFT )
  add_subdirectory( ${PROJECT_SOURCE_DIR}/thirdparty/kiss_fft )
  @@ -265,6 +270,9 @@ message( STATUS ">> Using FFT lib: ${FFT_LIB}" )
  message( STATUS ">> With include dirs: ${FFT_INCLUDE_DIRS}" )
  ####################################################################
  +######### Generate Version.hpp #####################################
  +configure_file( ${CMAKE_CURRENT_LIST_DIR}/CMake/Spirit_Version.hpp.in ${CMAKE_CURRENT_LIST_DIR}/include/utility/Version.hpp )
  +####################################################################
  ######### Dependencies that need to be built #######################
  include( GetQHull )
  