Added Region.shift

- Provided a default implementation using expand+contract in AbstractRegion
- Overrid the implementation in the subtypes

src/main/java/com/sk89q/worldedit/commands/SelectionCommands.java

@@ -407,10 +407,9 @@ public class SelectionCommands {
 
         try {
             Region region = session.getSelection(player.getWorld());
-            region.expand(dir.multiply(change));
-            region.contract(dir.multiply(change));
+            region.shift(dir.multiply(change));
             session.getRegionSelector(player.getWorld()).learnChanges();
-            
+
             session.getRegionSelector(player.getWorld()).explainRegionAdjust(player, session);
 
             player.print("Region shifted.");

src/main/java/com/sk89q/worldedit/regions/AbstractRegion.java

@@ -4,6 +4,7 @@ import java.util.Iterator;
 
 import com.sk89q.worldedit.BlockVector;
 import com.sk89q.worldedit.LocalWorld;
+import com.sk89q.worldedit.Vector;
 
 public abstract class AbstractRegion implements Region {
     /**
@@ -31,4 +32,9 @@ public abstract class AbstractRegion implements Region {
     public void setWorld(LocalWorld world) {
         this.world = world;
     }
+
+    public void shift(Vector change) throws RegionOperationException {
+        expand(change);
+        contract(change);
+    }
 }

src/main/java/com/sk89q/worldedit/regions/CuboidRegion.java

@@ -184,8 +184,7 @@ public class CuboidRegion extends AbstractRegion {
             }
         }
 
-        pos1 = pos1.clampY(0, world == null ? 127 : world.getMaxY());
-        pos2 = pos2.clampY(0, world == null ? 127 : world.getMaxY());
+        recalculate();
     }
 
     /**
@@ -236,10 +235,22 @@ public class CuboidRegion extends AbstractRegion {
             }
         }
 
+        recalculate();
+    }
+
+    private void recalculate() {
         pos1 = pos1.clampY(0, world == null ? 127 : world.getMaxY());
         pos2 = pos2.clampY(0, world == null ? 127 : world.getMaxY());
     }
 
+    @Override
+    public void shift(Vector change) throws RegionOperationException {
+        pos1 = pos1.add(change);
+        pos2 = pos2.add(change);
+
+        recalculate();
+    }
+
     /**
      * Get position 1.
      *

src/main/java/com/sk89q/worldedit/regions/EllipsoidRegion.java

@@ -136,6 +136,11 @@ public class EllipsoidRegion extends AbstractRegion {
     public void contract(Vector change) {
     }
 
+    @Override
+    public void shift(Vector change) throws RegionOperationException {
+        center = center.add(change);
+    }
+
     /**
      * Get the center.
      *

src/main/java/com/sk89q/worldedit/regions/Polygonal2DRegion.java

@@ -302,6 +302,23 @@ public class Polygonal2DRegion extends AbstractRegion {
         recalculate();
     }
 
+    @Override
+    public void shift(Vector change) throws RegionOperationException {
+        final double changeX = change.getX();
+        final double changeY = change.getY();
+        final double changeZ = change.getZ();
+
+        for (int i = 0; i < points.size(); ++i) {
+            BlockVector2D point = points.get(i);
+            points.set(i, new BlockVector2D(point.getX() + changeX, point.getZ() + changeZ));
+        }
+
+        minY += changeY;
+        maxY += changeY;
+
+        recalculate();
+    }
+
     /**
      * Checks to see if a point is inside this region.
      */

src/main/java/com/sk89q/worldedit/regions/Region.java

@@ -88,6 +88,14 @@ public interface Region extends Iterable<BlockVector> {
      */
     public void contract(Vector change) throws RegionOperationException;
 
+    /**
+     * Shift the region.
+     *
+     * @param change
+     * @throws RegionOperationException
+     */
+    public void shift(Vector multiply) throws RegionOperationException;
+
     /**
      * Returns true based on whether the region contains the point,
      *