* We need to be able to define a default set of EDNS options defined.
* We need to reset to the end of that set on each new query.
* We need to be able to "clear" that set while preserving it for the next query.
   This can also "clear" any per query options currently defined.

We should be able to do this by adding a few more index values into the array
to define a active set of options.   e.g.  a start index,  current index,
saved-current index.

new query -> start index=0, current index=saved-current index
+noednsopt -> start index=saved-current index, current index=saved-current index
saved-current index is set once all the default are defined.
a new option is added at current index freeing any existing option already there.