Added Entity interfaces, changed Player to implement these

By: Dinnerbone <dinnerbone@dinnerbone.com>

paper-api/src/org/bukkit/Entity.java

@@ -0,0 +1,35 @@
+
+package org.bukkit;
+
+/**
+ * Represents a base entity in the world
+ */
+public interface Entity {
+    /**
+     * Gets the entitys current position
+     *
+     * @return Location containing the position of this entity
+     */
+    public Location getLocation();
+
+    /**
+     * Gets the current world this entity resides in
+     *
+     * @return World
+     */
+    public World getWorld();
+
+    /**
+     * Teleports this entity to the given location
+     * 
+     * @param location New location to teleport this entity to
+     */
+    public void teleportTo(Location location);
+    
+    /**
+     * Returns a unique ID for this entity
+     * 
+     * @return Entity ID
+     */
+    public int getEntityID();
+}