...
See ?Release Notes for 1.9.0 RC2, Release Notes for 1.9.0 RC, Release Notes for 1.9.0 Beta, and Release Notes for 1.9.0 Alpha for other changed made since 1.8.
...
See ?Release Notes for 1.9.0 RC2, Release Notes for 1.9.0 RC, Release Notes for 1.9.0 Beta, and Release Notes for 1.9.0 Alpha for other changed made since 1.8.