Added a globals.py module for storing global variables. Created the
camera.py module which represents a 2D camera.
The character class is now using Rect for positioning instead of posx and posy integer variables.
Make sure the camera does not go outside of the 2D world.
The game objects and camera are now wrapped inside the World object. All camera and object updates are now done inside the World object.
Added the Megaman shooting animation and state.