document two recent changes

git-svn-id: https://svn.r-project.org/R/trunk@67078 00db46b3-68df-0310-9c12-caf00c1e9a41
options for external binary libs on Windows

git-svn-id: https://svn.r-project.org/R/trunk@67080 00db46b3-68df-0310-9c12-caf00c1e9a41
mention using external libs on Windows

git-svn-id: https://svn.r-project.org/R/trunk@67081 00db46b3-68df-0310-9c12-caf00c1e9a41
more on shell restrictions

git-svn-id: https://svn.r-project.org/R/trunk@67082 00db46b3-68df-0310-9c12-caf00c1e9a41
more manifestations of rand

git-svn-id: https://svn.r-project.org/R/trunk@67084 00db46b3-68df-0310-9c12-caf00c1e9a41
improve message

git-svn-id: https://svn.r-project.org/R/trunk@67086 00db46b3-68df-0310-9c12-caf00c1e9a41
No error on loadNamespace defining S4 generic, function of same name

- https://stat.ethz.ch/pipermail/r-help/2014-November/423789.html


git-svn-id: https://svn.r-project.org/R/trunk@67087 00db46b3-68df-0310-9c12-caf00c1e9a41