Merge branch 'master' into devel

* master:
  Fix group factors bug

From: Luke Zappia <lazappi@users.noreply.github.com>

git-svn-id: https://hedgehog.fhcrc.org/bioconductor/trunk/madman/Rpacks/splatter@131740 bc3139a8-67e5-0310-9ffc-ced21a209358