Implement achievement system: add achievement controller, UI components, and tests

stage/stage.gd

@@ -7,6 +7,7 @@ const SPEED_TEXTURE_NAME_TEMPLATE = "res://ui/topmenu/time&speed/time%s.png"
 
 const ItemDescription = preload("res://world/owniverse/item_description.gd")
 const WorldIndicators = preload("res://ui/indicators/world_indicators.gd")
+var achievements: Node
 var world_indicators: RefCounted
 var indicator_elapsed: float = 0.0
 var indicator_revision: int = -1
@@ -339,6 +340,10 @@ func _ready() -> void:
     create_new_universe()
     load_data()
     _refresh_universe_ui()
+    achievements = preload("res://ui/achievements/achievement_controller.gd").new()
+    add_child(achievements)
+    achievements.initialize(self)
+    achievements.update(0.0)
 
     g_counters.swipe.sec = 0.2
 
@@ -406,6 +411,7 @@ func _process(delta: float) -> void:
 
     owniverse.evolute_frame(delta, get_tree())
     _process_apocalypse(delta)
+    if achievements != null: achievements.update(delta)
     clock_display_elapsed += delta
     if clock_display_elapsed >= 0.1:
         clock_display_elapsed = fmod(clock_display_elapsed, 0.1)