update

git-svn-id: https://svn.r-project.org/R/trunk@66657 00db46b3-68df-0310-9c12-caf00c1e9a41
comments; cosmetic

git-svn-id: https://svn.r-project.org/R/trunk@66659 00db46b3-68df-0310-9c12-caf00c1e9a41
.onLoad() initializes "$" primitive method cache

git-svn-id: https://svn.r-project.org/R/trunk@66660 00db46b3-68df-0310-9c12-caf00c1e9a41