Modify: move code of related traffic in main.c to traffic.c
Want to split the traffic code from main.c
Modify: Remove code of related traffic

Remove code of related traffic in main.c to traffic.c
make main.c more clear
Add: traffic.o

traffic.c should be compiled
Add: bulletTime.o ball.o

bulletTime.c is a bullet time game
ball.c is the struct of a ball including draw and erease function.
Add: bulletTime game

a new game
Add: bullet Event Task function

bullet Event Task function will born new bullet from the eage of LCD
Fix: use double buffer to solbe slash windows

use two layer to display
Fix: let bullet can be applied for double buffer

change Bullet[] to BObj[] in order to apply for double buffer