0.0.4 - Camera movement and zooming.

+ Editor may now move with the WASD keys.
+ Editor may now zoom in and out with Ctrl + and -.

+ class MyCamera (+ global Camera)
global Camera holds the current window view.
! MyCamera has not been tested for Camera swapping.

+ All KeyTracker instances are defined in advance,
using the same names as their sf.Keyboard counterparts.
~ KeyTracker is now located in pysfml_game/key.py

! SCALE is now redundant, because Camera holds zoom.