This might mean we need additional type parameters, but I will see how
it's going to work out.
In theory, we could define a new trait for Seek+Read, but this would
mean that we couldn't contain owned streams.
For max flexibility, it's better to have additional type parameters
and use BorrowMut to allow ownership, and borrow.
That way, we have a common library to pull in from the main repository,
and a space for testing new code (in a partial implementation).
Next there will be generated object structures.
That will allow interaction between client and authentication attempts.
It also shows how cumbersome it is to deal with all these
generics ... but hey, you gotta do what you gotta do.
If boxes of pointers would be used, it would be easier to handle, but
enforces a certain memory model. That, of course, is not desired.
