Thanks Bryan!

Fixes issue #564

Thanks Pascal.

Fix #566

Fixes issue #565

Add missing dependencies.

The test required EOP data, but did not configure the data path.

Because of the addition of a static field for the GLONASS_EPOCH in AbsoluteDate
leap seconds had to be loaded to use AbsoluteDate. This commit restores the
previous behavior where AbsoluteDate can be used without loading leap seconds
first.

Thanks to Giuseppe Cavallaro for the translations.

Conflicts:
	src/changes/changes.xml
	src/main/java/org/orekit/errors/OrekitMessages.java
	src/main/resources/assets/org/orekit/localization/OrekitMessages_da.utf8
	src/main/resources/assets/org/orekit/localization/OrekitMessages_de.utf8
	src/main/resources/assets/org/orekit/localization/OrekitMessages_el.utf8
	src/main/resources/assets/org/orekit/localization/OrekitMessages_en.utf8
	src/main/resources/assets/org/orekit/localization/OrekitMessages_es.utf8
	src/main/resources/assets/org/orekit/localization/OrekitMessages_fr.utf8
	src/main/resources/assets/org/orekit/localization/OrekitMessages_gl.utf8
	src/main/resources/assets/org/orekit/localization/OrekitMessages_it.utf8
	src/main/resources/assets/org/orekit/localization/OrekitMessages_no.utf8
	src/main/resources/assets/org/orekit/localization/OrekitMessages_ro.utf8

This is mainly useful when sampling areas of interest that cover the
pole as the pole is singular for classical aiming directions (constant
azimuth or along track).

Thanks to Pascal for the very clever idea of diverting singularity!

Fixes #547

Set Jacoco fail and warning thresholds in CI script

See merge request orekit/orekit!11

As per Brouwer's hairy ball theorem, any vector field on the 2-sphere
has at least one zero. This implies that any implementation of
TileAiming interface has at least one points where the aiming direction
cannot be computed. The most typical example is aiming always towards
North pole, for which both poles are singular points.

Add staging repositories and ID of the Orekit signing key.