A new method getAlgorithmId() gives the algorithm identifier (DUVENHAGE,
CONSTANT_ELEVATION_OVER_ELLIPSOID, ...)

Fixes #381

Internally, we really use Gradient as the implementation in the library,
and DerivativeStructure in the tests for cross checks.

Fixes #385.

Fixes #386

Fixes #386

Direct location is performed in two phases, with a first intersection
being computed without corrections, then correction are applied and the
first solution is "refined". It was expected that the DEM cell did not
change there. Unfortunately, sometimes the refining did not find a
result in the same DEM cell. This was a very rare occurrence, and was
detected first on very ... rugged areas like mountains.

Now, when this rare event is detected, we restart a full-blown
intersection but starting from a point just after the exit of the
failing cell, when LOS is still above DEM and we prevent the algorithm
to find solutions backward (i.e. we prevent it from finding the previous
solution again and looping infinitely).

In case of big dump file, directory /tmp can be saturated with the
testCorruptedFiles test.

If the flag is set to true, we use in the DumpReplayer the default
MultiLayerModel. In case the user uses another model, one must asks the
user's model for debug purpose.
The dump files were updated to add the atmospheric refraction flag in
the direct loc and inverse loc lines.

refiningIntersection

Fixes #376

refiningIntersection

Fixes #376

Fixes #374

Fixes #373

Fixes #373

Fixes #373