* `exprs()` is no longer exported to avoid conflicts with `Biobase::exprs()`
  (#3638).

* The MASS package is explicitly suggested to fix CRAN warnings on R-devel
  (#3657).

* Set operations like `intersect()` and `setdiff()` reconstruct groups metadata (#3587).

* Using namespaced calls to `base::sort()` and `base::unique()` from C++ code
  to avoid ambiguities when these functions are overridden (#3644).

* Fix rchk errors (#3693).