Stan 2.19 release planned for Monday March 18th

There was a performance bug with individual matrix element access in 2.19.0 (see this thread for details) On Thursday at 1pm NYC time I’ll do a full release with whatever commit last passed all of the tests up and down the repos, which will either be 2.20.0 or 2.19.1 depending on if we have new features or just bug fixes, respectively.