Refactors GeoBoundingBoxQueryBuilder/-Parser

This add equals, hashcode, read/write methods, validation, separates toQuery
and JSON parsing and adds serialization and query generation tests.

Deprecates two types of initializing the bounding box: In our documentation we
speak about specifying top/left and bottom/right corner of a bounding box. Here
we also allow for top/right and bottom/left. This adds not only to the amount
of code but also testing needed w/o too much benefit for the user other than
more chances to confuse top/right/bottom/left/latitude/longitude IMHO.

Missing: The toQuery method with type set to "indexed" is not tested at the
moment.

Cleanup changes unrelated to base refactoring:
* Switched from type String to enum for types in GeoBoundingBoxQueryBuilder.
* Switched to using type GeoPoint for storing the bounding box coordinates
  instead of array of double values.

Relates to elastic#10217 for the query refactoring part.
Relates to elastic#12016 for how missing mappings are handled.

Adds a utility class for generating random geo data.

Adds some missing documentation.

Extend test to MEMORY type config

Fix final review comments and rebase

core/src/main/java/org/elasticsearch/common/Numbers.java

@@ -178,5 +178,4 @@ public static boolean isValidDouble(double value) {
         }
         return true;
     }
-
 }

core/src/main/java/org/elasticsearch/common/geo/GeoPoint.java

@@ -22,8 +22,8 @@
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import java.io.IOException;
 
+import java.io.IOException;
 
 import org.apache.lucene.util.BitUtil;
 import org.apache.lucene.util.XGeoHashUtils;
@@ -59,6 +59,10 @@ public GeoPoint(double lat, double lon) {
         this.lon = lon;
     }
 
+    public GeoPoint(GeoPoint template) {
+        this(template.getLat(), template.getLon());
+    }
+
     public GeoPoint reset(double lat, double lon) {
         this.lat = lat;
         this.lon = lon;
@@ -175,7 +179,7 @@ public static GeoPoint fromGeohash(long geohashLong) {
     public static GeoPoint fromIndexLong(long indexLong) {
         return new GeoPoint().resetFromIndexHash(indexLong);
     }
-    
+
     @Override
     public GeoPoint readFrom(StreamInput in) throws IOException {
         double lat = in.readDouble();

core/src/main/java/org/elasticsearch/common/geo/GeoUtils.java

@@ -23,6 +23,7 @@
 import org.apache.lucene.spatial.prefix.tree.QuadPrefixTree;
 import org.apache.lucene.util.SloppyMath;
 import org.elasticsearch.ElasticsearchParseException;
+import org.elasticsearch.common.Numbers;
 import org.elasticsearch.common.unit.DistanceUnit;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentParser.Token;