Refs #100425.  Removed another double-check for closed.  Modified getNetworkManager() to return null if the handle is closed.
Refs #100425.  Removed another double-check for closed.  Modified getNetworkManager() to return null if the handle is closed.

cawka/ndnx,svartika/ccnx,svartika/ccnx,cawka/ndnx,svartika/ccnx,ebollens/ccnmp,ebollens/ccnmp,svartika/ccnx,ebollens/ccnmp,cawka/ndnx,svartika/ccnx,svartika/ccnx,cawka/ndnx,cawka/ndnx,svartika/ccnx,ebollens/ccnmp