Add definitions for Minecraft 1.9 gameplay elements

Includes an API for AreaEffectCloud and rework of Sound enum to include new sound values.

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/event/entity/EntityDamageEvent.java

@@ -407,6 +407,12 @@ public class EntityDamageEvent extends EntityEvent implements Cancellable {
          * Damage: 1-4 (Thorns)
          */
         THORNS,
+        /**
+         * Damage caused by a dragon breathing fire.
+         * <p>
+         * Damage: variable
+         */
+        DRAGON_BREATH,
         /**
          * Custom damage.
          * <p>