Enable sparse Hamiltonians for simple_fciqmc.
Enable sparse Hamiltonians for simple_fciqmc.

Global variable use_sparse_hamil still to be removed, should be done
when the old input files are removed.

hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,ruthfranklin/hande,hande-qmc/hande