Painting improvements. Thanks CelticMinstrel!

Added interface to get/set the art and facing direction on paintings, and expanded painting break events to catch more cases (including fire and lightning); removed PaintingBreakByWorldEvent since it's identical to its superclass

src/main/java/org/bukkit/event/painting/PaintingBreakByWorldEvent.java

@@ -1,12 +0,0 @@
-package org.bukkit.event.painting;
-
-import org.bukkit.entity.Painting;
-
-/**
- * Triggered when a painting is removed by the world (water flowing over it, block damaged behind it)
- */
-public class PaintingBreakByWorldEvent extends PaintingBreakEvent {
-    public PaintingBreakByWorldEvent(final Painting painting) {
-        super(painting, RemoveCause.WORLD);
-    }
-}

src/main/java/org/bukkit/event/painting/PaintingBreakEvent.java

@@ -42,9 +42,20 @@ public class PaintingBreakEvent extends PaintingEvent implements Cancellable {
          */
         ENTITY,
         /**
-         * Removed by the world - block the painting is on is destroyed, water flowing over etc
+         * Removed by fire
          */
-        WORLD
-
+        FIRE,
+        /**
+         * Removed by placing a block on it
+         */
+        OBSTRUCTION,
+        /**
+         * Removed by water flowing over it
+         */
+        WATER,
+        /**
+         * Removed by destroying the block behind it, etc
+         */
+        PHYSICS,
     }
 }