[Rd] contribution offer: df() for non-centrality != 0

[Peter Ruckdeschel]

Hi Martin,

Martin Maechler wrote:
> but note that this is clearly too late for 2.3.0 :
> If you look at the release schedule at
>    http://developer.R-project.org/ 
> you see that  April 10 was "Feature Freeze".
>   
Yes, don't worry, I have been aware of this;

I did not mean to submit the code for 2.3.0, but just used
this version as a reference  to be "up-to-date".
> If it looks good -- and it does after a quick glimpse --
> it should be possible to be integrated for 2.3.1 though 
This would be fine !
Thank you

Peter