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

 cd ${0%update-libstd-tag}../doc

 mv libstdc++.tag libstdc++.tag.old

 wget http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/libstdc++.tag &&

 rm libstdc++.tag.old || mv libstdc++.tag.old libstdc++.tag