Added Falling sand/gravel entities to /remove command

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

@@ -25,6 +25,7 @@ package com.sk89q.worldedit;
 public enum EntityType {
     ARROWS,
     ITEMS,
+    FALLING_BLOCKS,
     PAINTINGS,
     BOATS,
     MINECARTS,

src/main/java/com/sk89q/worldedit/bukkit/BukkitWorld.java

@@ -36,6 +36,7 @@ import org.bukkit.entity.Arrow;
 import org.bukkit.entity.Boat;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.ExperienceOrb;
+import org.bukkit.entity.FallingSand;
 import org.bukkit.entity.HumanEntity;
 import org.bukkit.entity.Item;
 import org.bukkit.entity.LivingEntity;
@@ -602,6 +603,11 @@ public class BukkitWorld extends LocalWorld {
                     ent.remove();
                     ++num;
                 }
+            } else if (type == EntityType.FALLING_BLOCKS) {
+                if (ent instanceof FallingSand) {
+                    ent.remove();
+                    ++num;
+                }
             } else if (type == EntityType.MINECARTS) {
                 if (ent instanceof Minecart) {
                     ent.remove();