Add fire action to robot and bullets to arena
Create bullet renderer, update bullets by arena
Extract method
Change default speed for bullet so bullet is always faster than robot
Update bullet after fire so it moves out of the robot center
Bullet can hit robot and decrease its energy
Robot is dead if its energy is less than 0
Remove dead robots from arena
Don't draw dead robots in gui
Add possibility to scan other robots with radar
Put robots at random position in arena
Remove dead bullets