Add HUD class and integrate inventory background; update scene to draw HUD

.gitignore

@@ -0,0 +1 @@
+*.old.*

game/hud.rb

@@ -0,0 +1,9 @@
+class HUD
+  def initialize
+    @inventory_bg = Gosu::Image.new("assets/images/inventory.png", retro: true)
+  end
+
+  def draw
+    @inventory_bg.draw(0, 0, Float::INFINITY)
+  end
+end

game/scene.rb

@@ -1,5 +1,6 @@
 require_relative 'state'
 require_relative 'maze'
+require_relative 'hud'
 require_relative 'placeables/base'
 require_relative 'enemy/handler'
 require_relative 'character'
@@ -18,6 +19,8 @@ class Game < Scene
     @enemies = EnemyHandler.new
     @objects = ObjectHandler.new
 
+    @hud = HUD.new
+
     @camera = [0, 0]
 
     $bus.on(:player_move) do |pos|
@@ -44,6 +47,7 @@ class Game < Scene
     @character.draw
     @enemies.draw
     @objects.draw
+    @hud.draw
     draw_fog!
     draw_debug! if DEBUG
   end