made MetropolisSimulation::construct_what_string() be inline since it is called only once
during CeperleyMatrix::finish_*_update(), make sure the old inverse matrix was numerically accurate if a new one was computed during the step
make the CeperleyMatrix constructor explicit
it is now possible to tell a MetropolisSimulation to check for numerical error
call check_for_numerical_error() after equilibrating and after taking measurements
enforce a MetropolisSimulation as being dead once an exception is raised