Doc improvements for Path and PathDumper concepts (#331)

Merge #321

Merge #293

Merge

Small fixes related to BellmanFord (#51)

- Add a missing #include.
- Add a missing const keyword for negativeCycle().
- Test if negativeCycle() is const function.

Merge #68 (Port static graph implementation)

Merge

Make some graph member functions static (#311, #68)

Add a new build() function to StaticDigraph (#68)

This function builds the digraph from an arc list that
contains pairs of integer indices from the range [0..n-1].
It is useful in the cases when you would like to build a
StaticDigraph from scratch, i.e. you do not want to build
another digraph that can be copied using the other build()
function.

Extend the interface of StaticDigraph (#68)
with index(), arc() and node() functions similarly to
other static graph structures.

Add documentation for StaticDigraph (#68)

Small improvements + add tests for StaticDigraph (#68)

Port StaticDigraph from SVN -r3524 (#68)

Small fix in the doc (#179)

Add citations to the min mean cycle classes (#179, #184)

Merge #179 (Port the min mean cycle algorithms)

Add tolerance() functions for MMC classes (#179)

Separate group for the min mean cycle classes (#179)

Simplify comparisons in min mean cycle classes (#179)
using extreme INF values instead of bool flags.

Add HartmannOrlin algorithm class (#179)
This algorithm is an improved version of Karp's original method,
it applies an efficient early termination scheme.
The interface is the same as Karp's and Howard's interface.

Add Karp algorithm class (#179)
based on the MinMeanCycle implementation in SVN -r3436.
The interface is reworked to be the same as Howard's interface.

Rename MinMeanCycle to Howard (#179)

Add a detailed test file for MinMeanCycle and fix test_tools.h (#179)

Rename cyclePath() to cycle() in MinMeanCycle (#179)

Traits class + named parameters for MinMeanCycle (#179)

- Add a Traits class defining LargeValue, Tolerance, Path types.
LargeValue is used for internal computations, it is 'long long'
if the length type is integer, otherwise it is 'double'.
- Add named template parameters for LargeValue and Path types.
- Improve numerical stability: remove divisions from the internal
computations. If the arc lengths are integers, then all used
values are integers (except for the cycleMean() query function,
of course).

Rework and fix the implementation of MinMeanCycle (#179)

- Fix the handling of the cycle means.
- Many implementation improvements:
- More efficient data storage for the strongly connected
components.
- Better handling of BFS queues.
- Merge consecutive BFS searches (perform two BFS searches
instead of three).

This version is about two times faster on average and an order of
magnitude faster if there are a lot of strongly connected components.

Simplify the interface of MinMeanCycle (#179)
Remove init() and reset(), and move their content into findMinMean().

Port MinMeanCycle from SVN -r3524 (#179)
with some doc improvements