Merge pull request #464 in G/fastr from ~MICK.JORDAN_ORACLE.COM/fastr:feature/internal-pkgtest to master

* commit '74e951b8':
  destroy timed-out sub-processes
  pkgtest: move test timeout setting to test.package.R
  pkgtest: support vignettes and install Suggests
  pylint fix; remove old vignette setup code
  pkgtest: document issue with Suggests/vignettes
  pkgtest: revert to R_LIBS_USER owing to testInstalledPackage (sometimes) undefining R_LIBS
  pkgtest: create test files as tar.gz
  copyright fix
  fixes for rpart: implement La_rs, stats Approx/ApproxTest