Entirely rework cycle canceling algorithms (#180)

- Move the cycle canceling algorithms (CycleCanceling, CancelAndTighten)
into one class (CycleCanceling).
- Add a Method parameter to the run() function to be able to select
the used cycle canceling method.
- Use the new interface similarly to NetworkSimplex.
- Rework the implementations using an efficient internal structure
for handling the residual network.
This improvement made the codes much faster.
- Handle GEQ supply type (LEQ is not supported).
- Handle infinite upper bounds.
- Handle negative costs (for arcs of finite upper bound).
- Extend the documentation.

EXTRA_DIST += \

	scripts/bib2dox.py \

	scripts/bootstrap.sh \

	scripts/chg-len.py \

	scripts/mk-release.sh \

	scripts/unify-sources.sh \

	scripts/valgrind-wrapper.sh