Added IPoint.add(XY,Point).

We already had such a method for subtract(). Not sure how I managed to miss
add.

src/main/java/pythagoras/d/AbstractPoint.java

@@ -57,17 +57,22 @@ public abstract class AbstractPoint implements IPoint
         return result.set(x() + x, y() + y);
     }
 
+    @Override // from IPoint
+    public Point add (XY other, Point result) {
+        return add(other.x(), other.y(), result);
+    }
+
     @Override // from IPoint
     public Point subtract (double x, double y) {
         return subtract(x, y, new Point());
     }
 
-    @Override
+    @Override // from IPoint
     public Point subtract (double x, double y, Point result) {
         return result.set(x() - x, y() - y);
     }
 
-    @Override
+    @Override // from IPoint
     public Point subtract (XY other, Point result) {
         return subtract(other.x(), other.y(), result);
     }

src/main/java/pythagoras/d/IPoint.java

@@ -41,6 +41,10 @@ public interface IPoint extends XY, Cloneable
      * @return a reference to the result, for chaining. */
     Point add (double x, double y, Point result);
 
+    /** Translates this point by the specified offset and stores the result in the object provided.
+     * @return a reference to the result, for chaining. */
+    Point add (XY other, Point result);
+
     /** Subtracts the supplied point from {@code this}.
      * @return a new point containing the result. */
     Point subtract (double x, double y);

src/main/java/pythagoras/f/AbstractPoint.java

@@ -57,17 +57,22 @@ public abstract class AbstractPoint implements IPoint
         return result.set(x() + x, y() + y);
     }
 
+    @Override // from IPoint
+    public Point add (XY other, Point result) {
+        return add(other.x(), other.y(), result);
+    }
+
     @Override // from IPoint
     public Point subtract (float x, float y) {
         return subtract(x, y, new Point());
     }
 
-    @Override
+    @Override // from IPoint
     public Point subtract (float x, float y, Point result) {
         return result.set(x() - x, y() - y);
     }
 
-    @Override
+    @Override // from IPoint
     public Point subtract (XY other, Point result) {
         return subtract(other.x(), other.y(), result);
     }

src/main/java/pythagoras/f/IPoint.java

@@ -41,6 +41,10 @@ public interface IPoint extends XY, Cloneable
      * @return a reference to the result, for chaining. */
     Point add (float x, float y, Point result);
 
+    /** Translates this point by the specified offset and stores the result in the object provided.
+     * @return a reference to the result, for chaining. */
+    Point add (XY other, Point result);
+
     /** Subtracts the supplied point from {@code this}.
      * @return a new point containing the result. */
     Point subtract (float x, float y);