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.

 EXTRA_DIST += \

 	tools/CMakeLists.txt

 if WANT_TOOLS

 bin_PROGRAMS += \

 	tools/dimacs-solver \

 	tools/dimacs-to-lgf \

 	tools/lgf-gen

 dist_bin_SCRIPTS += tools/lemon-0.x-to-1.x.sh

 endif WANT_TOOLS

 tools_dimacs_solver_SOURCES = tools/dimacs-solver.cc

 tools_dimacs_to_lgf_SOURCES = tools/dimacs-to-lgf.cc

 tools_lgf_gen_SOURCES = tools/lgf-gen.cc