Make ReuseFactory Thread Safe
Make ReuseFactory Thread Safe

Access to the unused objects held by the ReuseFactory is made exclusive
for thread safety. Unfortunatly, it is not possible to lock the
ReuseFactory from the outside (preserving performance in single thread
applicationss). This is because the object deleter needs to also lock
the unused objects.

simquest/opensurgsim,simquest/opensurgsim,simquest/opensurgsim,simquest/opensurgsim