Bullet Collision

[karastoyanov]

[rayapetkova]

Last update: 02788f1

• Deleted the logic for collision in run_game and made a new file "collision.py" which has 3 functions - "collision", "check_user_plane_collision", "check_enemy_collision"
• In run_game we just use the two functions imported from collision.py
• Need to see if the armor and health bars of user_plane and enemies are being reduced enough