[Radiant] how to upgrade from 0.8 to 0.9?

[Eric]

The docs/wiki are way out of date and there is no RADIANT_* in
environment.rb (or environments/*) at all. I've found that 0.8.1 (or
some plugin) has disabled ctrl-right arrow, which I use to navigate
through text quite often, so I'd like to check whether 0.9 will fix it
or if it's a bigger problem.