r17670: 1) Refactor libnet context structure a bit, to have rpc connection

r17670: 1) Refactor libnet context structure a bit, to have rpc connection
   properties more consistently reflected.
2) Add domain open routine for lsa pipe - this is needed for ongoing
   name resolve function.

Tests (still neglected) and comments to follow.

rafal
(This used to be commit fe5652c2b8121bbe3b9932c43164035355478611)