PREPROCESSING OPTIONS USED IN THE SOURCES

Parallel execution:
      __MPI         MPI parallelization

GPU execution:
      USE_CUDA      Enable GPU support via CUDA FORTRAN
      USE_GPU_MPI   Enable support to CUDA-aware MPI
      USE_IPC       Enable intra-GPU communication via CUDA IPC primitives
      NO_CURAND     Disable CURAND random-number generation for initialization (use slower CPU initialization)

Libraries:
      __FFTW        FFT routines from internal FFTW library
      __FFTW3       FFT routines from external FFTW v3 library
      __LINUX_ESSL  Use blas/lapack/fft routines from IBM ESSL library
      __DFTI        FFT routines from external Intel MKL    
      __MKL         When doing "relax" computations, enable work around for bug in MKL (multithreaded GEMM will hang on AVX2)

IO / Reporting:
      __HDF5           Enable I/O using parallel HDF5
                       (Fortran 2003 features needed to compile)
      __CLOCK_SECONDS  Translate clock from HH:mm:ss to only seconds 
                       (default, see Modules/clocks.f90)


All other preprocessing flags are for debugging purposes and should not be
used unless you know what you are doing