Fixes issue #371.

Thanks to Lars Næsbye Christensen for the translations!
    
Fixes issue #343.

The ParameterDriver class has been introduced in Orekit for
the orbit determination feature.

This allows for example to retrieve the DEM elevation for a
latitude/longitude pair.

This can be used to set up min/max search lines.

This is still preliminary work, convergence seems slightly wrong.

This reverts commit b61d7ead.

This helps caller to set fix the min/max lines as we can provide
information about where the point is expected.

This algorithm is similar in spirit to the IGNORE_DEM_USE_ELLIPSOID, but
with a user-specified elevation instead of always using 0.0 elevation.

Implements feature #187.