Correct estimation of blocking start for multiple calculations
Correct estimation of blocking start for multiple calculations

Previously only the start position of the first calculation in the
output file was used for every calculation.  This is obviously not
correct in all cases (e.g. where different populations are used).  Fix
by evaluating start position for each calculation in turn by not
modifying the input argument.

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