subscriptionsObj does not need namespaceview
Support a test setup with arbitrary ro and rw ns views.
Declare size of done_hier, readily available. Reformatting.
Fix mapping logic for subscription begin.

Doesn't work right when subscribing to the anchor point of some namespace
mapping.

Bite the bullet. If subscribing to a hierarch, "", or "something/", then
append "x", so that it becomes "x" or "something/x", this produces correct
results from fromclient(), and we remove the "x" afterwards.
Extend subscriptions to sub-hierarchies.

Subscribing to a hierarchy results in notifications of objects that are
changed in the hierarchy and all sub-hierarchies.

Use x::hier to register all subscribed hierarchies. When the subscription
request for a hierarchy comes in, in addition to doing what's happening now,
also register the hierarchy in the x::hier container.

Remove the code that notifies the immediate hierarchy of a changed object
to searching the x::hier container, then walking up the hierarchy, and
notifying everyone.
Updated managed subscriptions to sub-hierarchy scope.

Now that the underlying client subscriptions cover the entire hierarchy and
all the sub-hierarchies, the managed subscription code needs to be updated
only to scan he entire hierarchy and all subhierarchies initially, and the
subscription update is going to take care of the ongoing updates.

Add a list of hierarchies to the implementation object, and when the connection
is made, prime the list with the top-level hierarchy.

The code that requests the directory listing of the hierarchy is factored out
into req_next_hierarchy() that takes the first hierarchy name off the list,
and calls enumerated() if the list is empty.

The directory results callback removes the names of all the subhierarchies
from the directory contents results, and adds them to the hierarchy list,
before calling update().

Remove the code that skips the names of all the subhierarchies from update(),
this is done before it gets called. If there are no more directory entries
to process, do not call enumerated(), call req_next_hierarchy(), instead.