support geocent (#60)

* support geocent

* Add inverse project radians

Signed-off-by: novpla <tuannn.bk@gmail.com>

src/main/java/org/locationtech/proj4j/Registry.java

@@ -194,6 +194,7 @@ private synchronized void initialize() {
         register("fouc", FoucautProjection.class, "Foucaut");
         register("fouc_s", FoucautSinusoidalProjection.class, "Foucaut Sinusoidal");
         register("gall", GallProjection.class, "Gall (Gall Stereographic)");
+        register("geocent", GeocentProjection.class, "Geocentric");
         register("geos", GeostationarySatelliteProjection.class, "Geostationary Satellite");
 //    register( "gins8", Projection.class, "Ginsburg VIII (TsNIIGAiK)" );
 //    register( "gn_sinu", Projection.class, "General Sinusoidal Series" );

src/main/java/org/locationtech/proj4j/proj/GeocentProjection.java

@@ -0,0 +1,21 @@
+package org.locationtech.proj4j.proj;
+
+import org.locationtech.proj4j.ProjCoordinate;
+import org.locationtech.proj4j.datum.GeocentricConverter;
+
+public class GeocentProjection extends Projection {
+
+  @Override
+  public ProjCoordinate projectRadians(ProjCoordinate src, ProjCoordinate dst) {
+    GeocentricConverter geocentricConverter = new GeocentricConverter(this.ellipsoid);
+    geocentricConverter.convertGeodeticToGeocentric(dst);
+    return dst;
+  }
+
+  @Override
+  public ProjCoordinate inverseProjectRadians(ProjCoordinate src, ProjCoordinate dst) {
+    GeocentricConverter geocentricConverter = new GeocentricConverter(this.ellipsoid);
+    geocentricConverter.convertGeocentricToGeodetic(dst);
+    return dst;
+  }
+}