Added the concept of a projectile.

src/main/java/org/bukkit/event/entity/ProjectileHitEvent.java

@@ -0,0 +1,11 @@
+package org.bukkit.event.entity;
+
+import org.bukkit.entity.Projectile;
+
+public class ProjectileHitEvent extends EntityEvent {
+
+    public ProjectileHitEvent(Projectile projectile) {
+        super(Type.PROJECTILE_HIT, projectile);
+    }
+
+}