Merge branch 'release-2.1'

Jenkinsfile

NOTICE.txt

Readme.md

checkstyle.xml

pom.xml

spotbugs-exclude-filter.xml

src/changes/changes.xml

src/design/dem-loading-class-diagram.puml

src/design/direct-location-class-diagram.puml

src/design/direct-location-sequence-diagram.puml

src/design/duvenhage-inner-recursion-activity-diagram.puml

src/design/duvenhage-top-loop-activity-diagram.puml

src/design/initialization-class-diagram.puml

src/design/initialization-sequence-diagram.puml

src/design/inverse-location-sequence-diagram.puml

src/design/parametric-los-class-diagram.puml

src/main/assembly/source-distribution-assembly.xml

.../java/org/orekit/rugged/adjustment/AdjustmentContext.java

...t/rugged/adjustment/GroundOptimizationProblemBuilder.java

...ed/adjustment/InterSensorsOptimizationProblemBuilder.java