extra_prints control over (commented-out) prints.
extra_prints control over prints in twolnL; check templates for NaNs.
Never zero-out completely any bin (JMTBAD define an EPS).
Schema
n_toy_limit -> 20k, sig_limit_lo starts at fitted mu_sig, hi ends at 1000 to not have to be smart; start bracketing limit at 5sig.