Sane initialisation of H00=<D0|H|D0> for FCIQMC calculations.
Sane initialisation of H00=<D0|H|D0> for FCIQMC calculations.

This will now be done automatically for a new system if (essentially) FCI
is also implemented for the new system.

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