All locally created nodes (CKTmk..() invocations in XXXsetup())
must be deleted in XXXunsetup()
Otherwise CKTmk..() invocations during a following CKTsetup()
will re-emit still used node numbers,
thus accidentally shorting nodes.
This patch fixes a little bit more complex cases,
which are local node variables which will start with value 0
and eventually be set with the result of a CKTmk..() invocations,
but might as well receive a node number from another node variable.
Here CKTdltNNum() must not be invoked if the node number is merely
a copy from another node variable.
rlar
c0921250b7