update: split collision detection in map and entity in CollisionHandler.java, implemented attack method in Player.java, updated key inputs in InputHandler.java #35 #34

add: CollisionHandler.java, update: implemented collision detection in IEntity.java and its implementations #18

add: Enum EntityType.java, update: implements Entity Interface in EnemyHandler.java, update: implemented EntityFactory.java, update: created player via factory in GameSceneController.java, update: Player.java #6

add EntityFactory.java, update GameSceneController.java, fix InputHandler.java, update Player.java #6