[Rd] 3D api for device

[l.bize at wanadoo.fr]

>> Hello.
>> Do the core team plans to add new device procedure
>> for 3D drawing in the NewDevDesc struct ?
>

> Some of us have talked about providing an extension mechanism so that 
> it is possible for third-party code to add to the list of device 
> procedures (without having to recompile R), but are only at the stage 
> of deciding that this would be a nice thing to do.

Ok.
The glx device is pretty advanced with  the 2D stuff and I'm thinking 
about the 3D stuff.

In a first time I would replace coordinates parameters with a list which 
hold the coordinates.
To be less intrusive I'm going to clone old procedures in new one with 
this coordinates list.

I'll keep you informed about this device,

    Laurent