reimplement enemy-filter loop (now enemy's reaction, and decision to possibly filter, is fully under enemy's control - physics, damage reaction, whether to filter or update enemy's state, etc.)

fcore/game-update.sml

@@ -8,6 +8,22 @@ struct
       val enemyTree = Enemy.generateTree enemies
       val player = Player.runPhysicsAndInput (game, input, enemyTree)
 
+      val projectiles = #projectiles player
+      val projectileTree = Projectile.generateTree projectiles
+
+      val enemies = Enemy.updateEnemyList
+        ( Vector.length enemies - 1
+        , enemies
+        , projectiles
+        , projectileTree
+        , walls
+        , wallTree
+        , platforms
+        , platformTree
+        , player
+        , graph
+        , []
+        )
     in
       { player = player
       , walls = walls