Merge branch 'maneuver-package' into develop

src/changes/changes.xml

src/main/java/org/orekit/errors/OrekitMessages.java

...rekit/forces/maneuvers/ConfigurableLowThrustManeuver.java

...a/org/orekit/forces/maneuvers/ConstantThrustManeuver.java

src/main/java/org/orekit/forces/maneuvers/Maneuver.java

...ers/propulsion/AbstractConstantThrustPropulsionModel.java

...euvers/propulsion/BasicConstantThrustPropulsionModel.java

...maneuvers/propulsion/ConstantThrustDirectionProvider.java

...g/orekit/forces/maneuvers/propulsion/PropulsionModel.java

...uvers/propulsion/ScaledConstantThrustPropulsionModel.java

...euvers/propulsion/ThrustDirectionAndAttitudeProvider.java

.../forces/maneuvers/propulsion/ThrustDirectionProvider.java

...it/forces/maneuvers/propulsion/ThrustPropulsionModel.java

.../org/orekit/forces/maneuvers/propulsion/package-info.java

...t/forces/maneuvers/trigger/DateBasedManeuverTriggers.java

.../forces/maneuvers/trigger/EventBasedManeuverTriggers.java

...org/orekit/forces/maneuvers/trigger/ManeuverTriggers.java

...ava/org/orekit/forces/maneuvers/trigger/package-info.java

...ces/assets/org/orekit/localization/OrekitMessages_da.utf8

...ces/assets/org/orekit/localization/OrekitMessages_de.utf8