Add convenient constructors in *RegionSelector classes

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

@@ -71,6 +71,14 @@ public class CuboidRegionSelector implements RegionSelector, CUIRegion {
         region.setPos2(pos2);
     }
 
+    public CuboidRegionSelector(LocalWorld world, Vector pos1, Vector pos2) {
+        this(world);
+        this.pos1 = pos1.toBlockVector();
+        this.pos2 = pos2.toBlockVector();
+        region.setPos1(pos1);
+        region.setPos2(pos2);
+    }
+
     public boolean selectPrimary(Vector pos) {
         if (pos.equals(pos1)) {
             return false;

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

@@ -79,6 +79,16 @@ public class CylinderRegionSelector implements RegionSelector, CUIRegion {
         }
     }
 
+    public CylinderRegionSelector(LocalWorld world, Vector2D center, Vector2D radius, int minY, int maxY) {
+        this(world);
+
+        region.setCenter(center);
+        region.setRadius(radius);
+
+        region.setMinimumY(Math.min(minY, maxY));
+        region.setMaximumY(Math.max(minY, maxY));
+    }
+
     public boolean selectPrimary(Vector pos) {
         if (!region.getCenter().equals(new Vector(0, 0, 0)) && pos.equals(region.getCenter())) {
             return false;

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

@@ -70,6 +70,13 @@ public class EllipsoidRegionSelector implements RegionSelector, CUIRegion {
         }
     }
 
+    public EllipsoidRegionSelector(LocalWorld world, Vector center, Vector radius) {
+        this(world);
+
+        region.setCenter(center);
+        region.setRadius(radius);
+    }
+
     public boolean selectPrimary(Vector pos) {
         if (pos.equals(region.getCenter()) && region.getRadius().lengthSq() == 0) {
             return false;

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

@@ -48,6 +48,14 @@ public class ExtendingCuboidRegionSelector extends CuboidRegionSelector {
         region.setPos2(pos2);
     }
 
+    public ExtendingCuboidRegionSelector(LocalWorld world, Vector pos1, Vector pos2) {
+        this(world);
+        pos1 = Vector.getMinimum(pos1,  pos2);
+        pos2 = Vector.getMaximum(pos1,  pos2);
+        region.setPos1(pos1);
+        region.setPos2(pos2);
+    }
+
     @Override
     public boolean selectPrimary(Vector pos) {
         if (pos.equals(pos1) && pos.equals(pos2)) {

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

@@ -45,6 +45,10 @@ public class SphereRegionSelector extends EllipsoidRegionSelector {
         region.setRadius(new Vector(radiusScalar, radiusScalar, radiusScalar));
     }
 
+    public SphereRegionSelector(LocalWorld world, Vector center, int radius) {
+        super(world, center, new Vector(radius, radius, radius));
+    }
+
     @Override
     public boolean selectSecondary(Vector pos) {
         final Vector diff = pos.subtract(region.getCenter());