Update the Fortran interface to avoid exposing C bindings to the user
- Modify the prototypes of spmGather, spmScatter, spmRedistribute, spmCopy, spm2Dense, spmGatherRHS, spmIntConvert to ease the development of the Fortran wrapper
- Add a Fortran test to validate scatter/gather interface
- Update the fortran interface to hide the complex _cloc/c_f_pointer requirement to the user
- Fix the MPI_Comm issue when discussing between Fortran and C
- Update the generation scripts accordingly