Moved camera into its own class, added CommonMethods for gosu methods outside of window.

lib/common_methods.rb

@@ -0,0 +1,12 @@
+class IMICFPS
+  module CommonMethods
+
+    def delta_time; $window.delta_time; end
+    def button_down?(id); $window.button_down?(id); end
+
+    def mouse_x; $window.mouse_x; end
+    def mouse_y; $window.mouse_y; end
+    def mouse_x=int; $window.mouse_x=int; end
+    def mouse_y=int; $window.mouse_y=int; end
+  end
+end