[Rd] link to an alias in another package

[Paul Gilbert]

In summary
> In some documentation for a package I am working on I have
>
>    \code{\link[stats]{varimax}}
>    \code{\link[stats]{promax}}
>
> The link to varimax works, but not the one to promax. Promax is an 
> alias under \name{varimax}.  ...

    \code(\link[stats:varimax]{promax}}

works but will probably break if promax is ever moved to its own Rd 
file. (From the discussion there is probably not a better general solution.)

    \code(\link{promax}}

works because stats is always installed, but is not a general solution 
because I have other cases where the package may not be installed.

    \code(\link[stats:promax]{varimax}}

which might be another (but presumably mistaken) interpretation of the 
Writing R Extensions documentation

>   \link[pkg:bar]{foo} to link to the package pkg with topic (file?)
>   foo and bar respectively.

does not work and also displays "varimax" in the text (which is not what 
I want).

Paul Gilbert