Thanks to Lucian Barbulescu for providing the translation.

Thanks to Ioanna Stypsanelli!

The detector can handle complex geographic zones, including non-convex
zones, zone split in non-connected sub-zones, zones with holes, and
zones containing the pole.

Fixes issue #163.

Fixes issue #154.

All these improvements have been contributed by Michael Turner. Many
thanks to him!

Note that Orekit still also support conventions 2003 in addition to
conventions 2010. However, as IERS does not provide anymore data to link
TIRF 2003 with ITRF, ITRF based on 2003 convention is not available.
ITRF can only be based on either 2010 conventions for CIO-based paradigm
or on 1996 conventions for equinox-based paradigm. 

Time-dependency can be secular trend and pulsations at various periods
(typically one year and one-half year). Since only the low order
coefficients are time-dependent, and in some case only linear drift is
available, great care has been taken to avoid unnecessary computation.
So the library may for example have a gravity field with most
coefficients constants, low order coefficients having full model with
drift and several harmonics, and intermediate coefficients having
simpler models, with less or even no harmonics at all. The computation
of the field will take care of everything and will not compute a large
number of sine and cosines that would ultimately be multiplied by 0.

For diagrams creation, we have switched to PlantUML, which can be
directly integrated into the maven build and eclipse and allow very
simple diagram creation and update without heavy tools.

The model all allows to compute at date t1 the effect of a
maneuver performed at date t0, without relying on any propagation (the
model applies directly to SpacecraftState instances).

instead of MEME, TEME and PEF). The implementation of TEME was also wrong (it was
really based on true equinox, not on mean equinox)

(first development by Aude)