Add ability to create graphical traces of different parameters

[grodtron]

We should be able to track different parameters inside the simulation, and launch either static or dynamic plots of them.

• Track and statically plot counter values
• Track and statically plot latencies
  • Latency is the time delta from read at module A to write at module B
• Track and statically plot throughputs
  • Throughput is the number of writes / second at a given port/PE
• Dynamically plot any of the above.

(Depends on #9)