Changed EditSessionBlockDelegate.getHeight's return to match what Bukkit's worldheightheight methods return

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

@@ -58,6 +58,6 @@ public class EditSessionBlockChangeDelegate implements BlockChangeDelegate {
     }
 
     public int getHeight() {
-        return editSession.getWorld().getMaxY();
+        return editSession.getWorld().getMaxY() + 1;
     }
 }