Major improvement in the cost scaling algorithm

- Add a new variant that use the partial augment-relabel method.
- Use this method instead of push-relabel by default.
- Use the "Early Termination" heuristic instead of "Price Refinement".

Using the new method and heuristic the algorithm proved to be
2-2.5 times faster on all input files.

 #!/bin/bash

 for((i=1;i<50;i++))

 do

     echo -n $i ''

     edge_lookup 100 $i

 done