Add some simple support for capturing external files that are included into the main NS files via the "source" command, and stuffing them into the experiment archive.
Add some simple support for capturing external files that are included
into the main NS files via the "source" command, and stuffing them
into the experiment archive.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome