better spawn, heart ui, dash, new map

scripts/wave_node.gd

@@ -0,0 +1,23 @@
+class_name WaveNode extends Node2D
+
+@export var spawn_interval := 0.2
+signal finished;
+var entities := 0;
+
+func _ready() -> void:
+	entities = get_child_count()
+
+func spawn_wave():
+	if get_child_count() == 0:
+		finished.emit()
+		return;
+	
+	for c : Spawner in get_children():
+		c.spawn();
+		c.finished.connect(entity_left)
+		await get_tree().create_timer(spawn_interval).timeout
+		
+func entity_left():
+	entities -= 1
+	if entities <= 0:
+		finished.emit()