Entirely rework CapacityScaling (#180)

- Use the new interface similarly to NetworkSimplex.
- Rework the implementation using an efficient internal structure
for handling the residual network. This improvement made the
code much faster (up to 2-5 times faster on large graphs).
- Handle GEQ supply type (LEQ is not supported).
- Handle negative costs for arcs of finite capacity.
(Note that this algorithm cannot handle arcs of negative cost
and infinite upper bound, thus it returns UNBOUNDED if such
an arc exists.)
- Extend the documentation.

 #!/bin/sh

 # Run in valgrind, with leak checking enabled

 valgrind -q --leak-check=full "$@" 2> .valgrind-log

 # Save the test result

 result="$?"

 # Valgrind should generate no error messages

 log_contents="`cat .valgrind-log`"

 if [ "$log_contents" != "" ]; then

         cat .valgrind-log >&2

         result=1

 fi

 rm -f .valgrind-log

 exit $result