- "modelnet" parameter in cfg is now a no-op
- "modelnet_order" parameter in cfg is required,
  listing order in which networks are indexed to
  the model
- modified "model_net_set_params" signature
- updated tests to use the new interface

Adding collective modeling functions in model-net (currently only dragonfly/torus models support it)

- NOTE: shim just forces packet size to a huge number

- NOTE: the current scheduling policy of FCFS is hard-coded, this will change
  in future revisions
- NOTE: random number generation has changed due to the differences in
  scheduling and packet ordering. Hence, results may be slightly different from
  runs prior to this commit

- currently stupid, stats don't really mean
  anything when pulling
- enable manually by setting do_pull = 1 (no
  cmdline option yet)

- pull itself not yet tested