Added world.getMaxHeight (currently static until 1.8)

By: Dinnerbone <dinnerbone@dinnerbone.com>

paper-api/src/main/java/org/bukkit/World.java

@@ -667,6 +667,15 @@ public interface World {
      */
     public double getHumidity(int x, int z);
 
+    /**
+     * Gets the maximum height of this world.
+     *
+     * If the max height is 100, there are only blocks from y=0 to y=99.
+     *
+     * @return Maximum height of the world
+     */
+    public int getMaxHeight();
+
     /**
      * Represents various map environment types that a world may be
      */