Added method to obtain a vector from two points.

Whatdya know, I already need it.

src/main/java/pythagoras/d/Vectors.java

@@ -32,6 +32,13 @@ public class Vectors
         return new Vector(magnitude * Math.cos(angle), magnitude * Math.sin(angle));
     }
 
+    /**
+     * Creates a vector from {@code from} to {@code to}.
+     */
+    public static Vector from (IPoint from, IPoint to) {
+        return new Vector(to.x() - from.x(), to.y() - from.y());
+    }
+
     /**
      * Returns the magnitude of the specified vector.
      */

src/main/java/pythagoras/f/Vectors.java

@@ -32,6 +32,13 @@ public class Vectors
         return new Vector(magnitude * FloatMath.cos(angle), magnitude * FloatMath.sin(angle));
     }
 
+    /**
+     * Creates a vector from {@code from} to {@code to}.
+     */
+    public static Vector from (IPoint from, IPoint to) {
+        return new Vector(to.x() - from.x(), to.y() - from.y());
+    }
+
     /**
      * Returns the magnitude of the specified vector.
      */