primarycensored 1.5.1

This patch release fixes a performance regression introduced in 1.5.0 that slowed the Stan likelihood for positive-support delays.

Bug fixes

• Fixed a performance regression in the Stan primarycensored_lpmf and primarycensored_lcdf functions for positive-support delays. After the lower-truncation guard was relaxed in 1.5.0 to support negative L, every likelihood evaluation for positive-support delays entered a truncation-normalisation block that cancels to a no-op but still adds gradient calculations (an exp/log_diff_exp per call), giving a roughly 30% slowdown on the likelihood block. The guard now skips this block unless there is a finite D, a strictly positive L, or a finite L on a real-support distribution, restoring 1.4.0 performance without changing results or losing the negative-support behaviour. Thanks to @sbfnk for reporting (#323).

Full Changelog: v1.5.0...v1.5.1