use <attach> to dynamically export optional components in the search space

Following is the prototype 

``` r

nev <- new.env()

get_new_var <- function(){

  attach(nev, pos = 2L, name = "pkg:internals")
}


nev$`%+%` <- function(x, y){
  x*y
}
```

Note that the above needs to be tuned for the fact that **it does not detach on the unload** of the package. 