start refactoring pong entities to use classes

src/ball.h

@@ -0,0 +1,21 @@
+#ifndef PLAYER_H
+#define PLAYER_H
+
+#include <stdint.h>
+#include "config.h"
+
+class Ball {
+  private:
+    uint8_t _x, _y;
+    int8_t _direction_x, _direction_y;
+
+  public:
+    void move();
+    void bounce_on_pad();
+    void bounce_on_sides();
+    void reset_position ();
+    uint8_t get_x();
+    uint8_t get_y();
+};
+
+#endif