This is a partial implementation for issue #855.

The names should *not* be extracted too early, at least the force models
must be completed before they can be retrived reliably. However, once
they are set up we can ask the MatricesHarvester to give the columns
names, even if propagation has not started yet.

The default implementation throws un UnsupportedOperationException which
will be removed when the method is implemented in all propagators (but
not before 12.0 for compatibility reasons).

declaring the method already at highest level will allow getting rid
(deprecating them first) of several clumsy classes in estimation
package.

Allowed Brouwer-Lyddane model to work for the critical inclination of 63.4°

Closes #869

See merge request orekit/orekit!223

Fixed handling of multiple historical eccentricities for a same station.

Closes #867

See merge request orekit/orekit!222

Fixes #867

Drop StringBuffer usage

See merge request orekit/orekit!219

Fixed writing of whitespace characters in CPF writer.

Closes #868

See merge request orekit/orekit!221

Fixes #868

Fixed BStar estimation in TLE-based orbit determination.

Closes #864

See merge request orekit/orekit!220

Fixed #864

Fixes #861

Add derivatives with respect to maneuvers start and stop dates.

Closes #856, #853, and #848

See merge request orekit/orekit!218