Import SummarizedExperiment to avoid warnings

Now estimates number of each gene type

git-svn-id: https://hedgehog.fhcrc.org/bioconductor/branches/RELEASE_3_5/madman/Rpacks/splatter@129128 bc3139a8-67e5-0310-9ffc-ced21a209358

* master:
  Bump version number
  Update scDD reference
  Add addGeneLengths to vignette
  Add addGeneLengths tests
  Add addGeneLengths function
  Update Roxygen version
  Update README
  Add bioc-devel to Travis

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

git-svn-id: https://hedgehog.fhcrc.org/bioconductor/trunk/madman/Rpacks/splatter@126415 bc3139a8-67e5-0310-9ffc-ced21a209358

git-svn-id: https://hedgehog.fhcrc.org/bioconductor/trunk/madman/Rpacks/splatter@125902 bc3139a8-67e5-0310-9ffc-ced21a209358

Getting note about scDatEx, but think it should be fine...