[Orekit Developers] Preparation for next release

[Luc Maisonobe <Luc.Maisonobe@c-s.fr>]

Hi all,

We are planning to release the next version of Orekit soon. This will be
a major release: 7.0. This version mainly includes the complete DSST
semi-analytical propagator, as the project to include short periodics
terms has been a success, and it also includes the extension to second
order derivatives for many models (Cartesian coordinates, angular
coordinates, attitude modes, ...).

I think the current status is feature-complete. We need to update to the
new version of Apache Commons Math (3.4 will hopefully been released
very soon now). This version brings corrections useful for Orekit. We
also need to remove old deprecated methods and classes, as
we can do on a major version release.

If you think anything else should be included for 7.0, please chime in.
Remember that we can introduce incompatible changes in a major release
like 7.0, but once it is out we will not be able to introduce such
changes in 7.X and will have to wait for 8.0. So if you need some
breaking new feature, now is the time to introduce it.

best regards,
Luc