moved NdbWaiter, m_ndb_cluster_connection, to impl class
    moved node selection things to cluster connection
    moved all private things to impl class
    added opts for shared memory and node selection
    changed opts handling somewhat; introduced enum for options and common handling of option variables
    added checks for transporter support
    automatic addition of shared mem transporters
    moved wait_until_ready code to cluster connection
    added control of usage of new node selection method