Initial setup
Adding a red ball in the center
Ball moves
Ball bounces from the top of the screen
Revert "Ball bounces from the top of the screen"

This reverts commit 5f972096b5cce6eec93f9065ccd9669766ae44ef.
Ball bounces off the top of the screen
Ball bounces: bottom
refactor

- Bounce_off_edge
- dx, dy
Randomize initial movement of ball

- Always with a random angle, +- 30 degrees to to the right
- half of the times to the left as well
Add score text
Giving points to players

Update score text when a ball goes outside
Create a Paddle for each player
Move both paddles up and down

Keyboard W for UP
Keyboard S for DOWN

http://www.libgosu.org/rdoc/Gosu/Window.html#button_down%3F-instance_met
hod
Refactor Paddle Speed

… and accelerate it a bit for it to be a bit snappier
Paddles stay in the screen

We limit their up and down methods
Refactor game::update method

Game::Update method is more readable now

- move_paddle_if_keypress
- check_off_bounces
Make the ball bounce off the paddle
Creating an AI to play as the left paddle
Pressing escape quits the game
Refactor exit with esc code