Added HUD widgets, make Boot and Close use button_up instead of button_down

lib/hud/widgets/ammo.rb

@@ -0,0 +1,29 @@
+class IMICFPS
+  class HUD
+    class AmmoWidget < HUD::Widget
+      def setup
+        @text = Text.new("")
+        @background = Gosu::Color.new(0x88222222)
+      end
+
+      def draw
+        Gosu.draw_rect(
+          @text.x - @margin, @text.y - @margin,
+          @text.width + @margin * 2, @text.height + @margin * 2,
+          @background
+        )
+        @text.draw
+      end
+
+      def update
+        if (Gosu.milliseconds / 1000.0) % 1.0 >= 0.9
+          random = "#{rand(0..999)}".rjust(3, "0")
+          @text.text = "Pistol\nAMMO: #{random}"
+        end
+
+        @text.x = window.width - (@margin * 2 + @text.width)
+        @text.y = window.height - (@margin * 2 + @text.height)
+      end
+    end
+  end
+end