Java API: adding missing class

modules/java/src/java/features2d+DMatch.java

+package org.opencv.features2d;
+
+//C++: class DMatch
+//javadoc: DMatch
+public class DMatch {
+	
+	//javadoc: DMatch::queryIdx
+	public int queryIdx;
+	//javadoc: DMatch::trainIdx
+	public int trainIdx;
+	//javadoc: DMatch::imgIdx
+	public int imgIdx;
+	//javadoc: DMatch::distance
+	public float distance;
+    
+    
+    //javadoc: DMatch::DMatch()
+    public DMatch() {
+    	this(-1, -1, Float.MAX_VALUE);
+	}
+	
+	
+    public DMatch( int _queryIdx, int _trainIdx, float _distance ) {
+    	queryIdx = _queryIdx;
+    	trainIdx = _trainIdx;
+    	imgIdx = -1;
+    	distance = _distance; 
+    }
+    
+    
+    public DMatch( int _queryIdx, int _trainIdx, int _imgIdx, float _distance ) {
+    	queryIdx = _queryIdx;
+    	trainIdx = _trainIdx;
+    	imgIdx = _imgIdx;
+    	distance = _distance; 
+    }
+
+    // less is better
+    boolean lessThan(DMatch it) {
+        return distance < it.distance;
+    }
+
+
+	@Override
+	public String toString() {
+		return "DMatch [queryIdx=" + queryIdx + ", trainIdx=" + trainIdx
+				+ ", imgIdx=" + imgIdx + ", distance=" + distance + "]";
+	}
+
+}