Added a way to generate net weights from upper bound placement as well as lower bound
Fixed a div#0 bug with zero or one pin HPWL nets
Small cleanup
Now uses a jacobi preconditioner ; seems faster
Stopping error of CG is now set by the caller from the desired per pin error
Added some simplistic benchmarks from Coursera's VLSICAD course
Capability of nets to add new pins to a matrix