Traverse a DList and insert / remove in place?

[Armando]

Say I have a DList. I am looking for a vanilla way to 
insert/remove elements in place while traversing that list.

```d
import std.container : DList;

struct myType{
    int id;
    // [...] other stuff
}

auto list = DList!myType();

// [...] populate list with elements
```

To remove the element with id=3 I can do:
```d
list.linearRemove(list[].find!(a => a.id==3).take(1));
```
but according to [this 
post](https://forum.dlang.org/post/mailman.3110.1356864469.5162.digitalmars-d@puremagic.com) linearRemove might be less efficient than remove and remove can't be used. Also in the example above, finding the needle is easy but my case would involve more complicated scenarios that I am relunctant to bury into find's predicate.

I would like to do something like traversing a DList, operating 
on the current element, and potentially removing that element or 
inserting a new one before/after it - an easy operation if you 
code a DList yourself. Maybe I missed something?

```d
// Traverse and operate on current element
foreach(element; list)
{
     // [...] do something long and complicated with m, throw a 
random number rand

     if(rand < 0.5)
         list.removeInPlace(); // remove 'element'
     else
         list.insertInPlace(myType(...)); // insert a new element 
"here" (before/after 'element')
}
```

Any way to achieve this simply with D? E.g. is there a way to 
extract the 'reading head' of a list being traversed and to use 
that head as a range into the remove, insertAfter, insertBefore 
functions?