WIP.  Main structure of Hellmann--Feynmann sampling.
WIP.  Main structure of Hellmann--Feynmann sampling.

A few pieces left to do (marked by TODO)...

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