added on_order handler to entities and components, added visibility map

lib/camera.rb

@@ -1,6 +1,7 @@
 class IMICRTS
   class Camera
     attr_reader :viewport, :position, :velocity, :zoom, :drag
+
     def initialize(viewport:, scroll_speed: 10, position: CyberarmEngine::Vector.new(0.0, 0.0))
       @viewport = CyberarmEngine::BoundingBox.new(viewport[0], viewport[1], viewport[2], viewport[3])
       @scroll_speed = scroll_speed
@@ -15,7 +16,9 @@ class IMICRTS
       @grab_drag = 0.5 # Used when camera is panned using middle mouse button
     end
 
-    def window; $window; end
+    def window;
+      $window;
+    end
 
     def draw(&block)
       if block