Small bug fixes (#180)

Rename a private type in MCF classes (#180)

The new MCF algorithms define a private map type VectorMap,
which could be misleading, since there is an other VectorMap
defined in lemon/bits/vector_map.h. Thus the new type is
is renamed to StaticVectorMap.

Adds tests for the new MCF algorithms (#180)

Rework the MCF test file to help extending it (#180)

Fixes in the heap concept to avoid warnings (#180)

Add citations to CycleCanceling (#180, #184)

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.