1. Port Forwarding Support

  When a SAGE application cannot directly access display nodes,
  set TCP port forwarding from a gateway node to the display nodes and
  configure the application to connect to the display nodes 
  via the gateway node.
 
  For example, create a ssh tunnel on the gateway node as follows 

  ssh -g -f -L gatewayPort:displayIP:displayPort displayIP -N

  The tile display config has a new line starting by "Forward"

  DisplayNode
        IP displayIP:displayPort
        Forward gatewayIP:gatewayPort
        Monitors 1 (0,0)

  Application config file (atlantis.conf, render.conf, ....)  has 
  a new parameter called "portForwarding"

  If portForwarding = 1, the application tries to connect 
  to gatewayIP:gatewayPort.
  If portForwarding = 0, the application tries to connect 
  to displayIP:displayPort (normal case).

  * If omit 'displayPort' in the tile config file, 'receiverStreamPort' 
    in 'fsManager.conf' is used as 'displayPort.'