Correct precision aggregation in normal approx. Correct for priors in approx.
Correct precision aggregation in normal approx. Correct for priors in approx.

Was previously averaging rather than summing worker-level precisions in the
posterior_approx_distributed() function. This reduced acceptance rates
significantly for the variance hyperparameter steps, in particular. The
averaging step has now been removed and acceptance rates have vastly improved.

Also corrected proposal precisions in rmh_master*() functions to account for
multiple appearances of prior precision in the worker-level quantities.

awblocker/quantitation,awblocker/quantitation,awblocker/quantitation