cfrnow 0.2.0

• fit_cfr() and simulate_linelist() take a Weibull() onset-to-death (and
  onset-to-recovery) delay, alongside LogNormal() and Gamma().
• Delay parameterisation now uses distspec's exported natural_params() instead
  of an internal helper; cfrnow requires distspec (>= 0.1.0).
• New "Stratified and partially-pooled CFR" vignette: no-, complete- and
  partial-pooling fits, with per-group summary() output.
• pp_check_cfr() runs a posterior-predictive check. It draws replicate line
  lists from the posterior, replays the real-time truncation, and compares
  observed death counts (and recoveries, in a two-outcome fit) and onset-to-death
  delays against the replicates.
• summary() takes an ascertainment_ratio argument to correct the CFR when
  fatal and non-fatal cases enter the line list at different rates. Defaults to 1.
• fit_cfr() accepts intercept-free CFR formulas (e.g. cfr ~ 0 + group),
  fitting one logit-CFR per group with cfr_prior on those coefficients.
• summary() reports a CFR per group for a cfr ~ group fit, one cfr[<group>]
  row per group.