Merge branch 'master' of ssh://www.orekit.org/rugged-main

src/site/markdown/tutorials/direct-location.md

src/site/markdown/tutorials/inverse-location.md

src/site/markdown/tutorials/tile-updater.md

src/test/java/org/orekit/rugged/api/RuggedBuilderTest.java

src/test/java/org/orekit/rugged/api/RuggedTest.java

...est/java/org/orekit/rugged/errors/RuggedMessagesTest.java

...org/orekit/rugged/intersection/AbstractAlgorithmTest.java

...rg/orekit/rugged/intersection/BasicScanAlgorithmTest.java

...rugged/intersection/duvenhage/DuvenhageAlgorithmTest.java

...kit/rugged/intersection/duvenhage/MinMaxTreeTileTest.java

...orekit/rugged/linesensor/SensorMeanPlaneCrossingTest.java

.../orekit/rugged/raster/CheckedPatternElevationUpdater.java

...java/org/orekit/rugged/raster/CliffsElevationUpdater.java

src/test/java/org/orekit/rugged/raster/CountingFactory.java

...java/org/orekit/rugged/raster/RandomLandscapeUpdater.java

src/test/java/org/orekit/rugged/raster/SimpleTileTest.java

src/test/java/org/orekit/rugged/raster/TilesCacheTest.java

...rg/orekit/rugged/raster/VolcanicConeElevationUpdater.java

...t/java/org/orekit/rugged/utils/ExtendedEllipsoidTest.java