minor changes to model-net plug-in: (1) making the torus network's chunk size configurable (2) handling some edge cases which we haven't encountered so far but its good to have them for future

- these calls should be made by the top level model only, so that all
  results are consolidated into the same subdirectory
- add corresponding calls to modelnet test programs

- save previous cumulative time values rather than actually reversing
  calculation in order to avoid minor discrepancies introduced by
  rounding error

- not producing correct results yet

- also tweak temporary hard-coded network parameters in loggp method to
  look somewhat like Tukey IB network for quick sanity checking of
  output

- right now this runs out of event memory when you run it

- just a slightly modified copy of normal modelnet test for now; will
  update to use as the primary test harness for loggp validation

also misc update to how loggp method plugs into modelnet

- just a copy of simplenet with variables and functions renamed for now

Adding statistics collection using lp-io in model-net API (comes from the simple-net stats collection), works for simple-net, torus and the dragonfly network models (updating comments)

Adding statistics collection using lp-io in model-net API (comes from the simple-net stats collection), works for simple-net, torus and the dragonfly network models