[Rd] nlminb - Port library codes

[John C Nash]

Having looked at documentation and codes, I'm still looking to find out 
who did the installation of the Port libraries. As I work on 
optimization code improvements, there are often choices of settings 
(tolerances etc.), and I'd prefer to learn if there are particular 
reasons for choices before diving in and making any adjustments.

It is also worth giving credit where it is due. Given the complexity of 
the Port code structure, adapting them to R must have been a lot of work.

JN