Fixed crash due to old code from initial import, various clean up.

lib/cyberarm_engine/common.rb

@@ -0,0 +1,27 @@
+module CyberarmEngine
+  module Common
+    def push_state(klass, options={})
+      $window.push_state(klass, options)
+    end
+
+    def current_state
+      $window.current_state
+    end
+
+    def pop_state
+      $window.pop_state
+    end
+
+    def show_cursor
+      $window.show_cursor
+    end
+
+    def show_cursor=boolean
+      $window.show_cursor = boolean
+    end
+
+    def draw_rect(x, y, width, height, color, z = 0)
+      $window.draw_rect(x,y,width,height,color,z)
+    end
+  end
+end