Added BlockVector[2D].toBlockVector[2D] overrrides.

This returns the current object, for an instant speed boost :)

src/main/java/com/sk89q/worldedit/BlockVector.java

@@ -97,4 +97,9 @@ public class BlockVector extends Vector {
                 (Integer.valueOf((int) y).hashCode() << 12) ^
                 Integer.valueOf((int) z).hashCode();
     }
+
+    @Override
+    public BlockVector toBlockVector() {
+        return this;
+    }
 }

src/main/java/com/sk89q/worldedit/BlockVector2D.java

@@ -90,4 +90,9 @@ public class BlockVector2D extends Vector2D {
         return (Integer.valueOf((int) x).hashCode() >> 13) ^
                 Integer.valueOf((int) z).hashCode();
     }
+
+    @Override
+    public BlockVector2D toBlockVector2D() {
+        return this;
+    }
 }