"zipper tile" creation for non overlapping DEM whatever tiles resolution

src/main/java/org/orekit/rugged/api/RuggedBuilder.java

src/main/java/org/orekit/rugged/errors/DumpReplayer.java

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

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