Move test to see if we've found all electrons to an outer loop.
Move test to see if we've found all electrons to an outer loop.

Branching in a tight loop is expensive.  Rather than testing every byte
in a bit string, test every integer.  This cuts down the cost of
decoding 21905 determinants 10000 times from 18.1s to 16.7s (both for
DET_SIZE=32 and DET_SIZE=64, 8 electrons and 44 basis functions).

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