Add missing imports to game-manager

modules/game/game-manager.scm

@@ -1,10 +1,15 @@
 (define-module (game game-manager)
-    #:pure
-    #:use-module (scheme base)
-    #:use-module (ces system html-canvas-renderer)
-    #:use-module (game level-manager)
-    #:export (init-game-entities
-              init-game-systems))
+  #:pure
+  #:use-module (scheme base)
+  #:use-module (dom document)
+  #:use-module (dom element)
+  #:use-module (dom image)
+  #:use-module (dom window)
+  #:use-module (dom canvas)
+  #:use-module (ces system html-canvas-renderer)
+  #:use-module (game level-manager)
+  #:export (init-game-entities
+            init-game-systems))
 
 (define canvas (get-element-by-id "canvas"))
 (define context (get-context canvas "2d"))
@@ -17,6 +22,6 @@
           (create-room! room-background 0 0 128 64)))
 
 (define (init-game-systems) 
-    "Returns a list of initial game systems.  
+  "Returns a list of initial game systems.  
 Note: Systems are executed sequentially.  "
-    (list (create-html-canvas-renderer context)))
+  (list (create-html-canvas-renderer context)))