[Orekit Developers] Another change in orbit determination

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

Hi all,

It occurred to me that the name for angular measurements (the Angular
class) was a bad choice. We will add at some point in the future another
set of angular measurement for right ascension/declination (using
optical telescopes taking picture of satellites on the stars background,
thus reducing errors due to flexions in big antennas and refraction models).

So I took the opportunity of 9.0 to change the name from Angular to
AngularAzEl, and we can later on add AngularRaDec.

Those of you that have set up continuous integration from the
development master branch will have to update your code
accordingly.

sorry for the inconvenience

Luc