add lantern object and implement light management in player and environment

src/de/miaurizius/jgame2d/entity/Entity.java

@@ -70,6 +70,7 @@ public class Entity {
     public int mana;
     public Entity currentWeapon;
     public Entity currentShield;
+    public Entity currentLight;
     public Projectile projectile;
     public ArrayList<Entity> inventory = new ArrayList<>();
     public final int maxInvSize = 20;
@@ -85,6 +86,7 @@ public class Entity {
     public int knockbackVal;
     public boolean stackable;
     public int amt = 1;
+    public float lightRadius;
 
     public Entity(GamePanel panel) {
         this.panel = panel;