Update movement to mimic i6_engine

[kruserr]

void Player::keyboard_input(SDL_Event event)
{
    switch (event.type)
    {
        case SDL_KEYDOWN:
            switch (event.key.keysym.sym)
            {
                case SDLK_LEFT:
                    keyboard_hold_left = true;
                    break;
                case SDLK_a:
                    keyboard_hold_left = true;
                    break;

                case SDLK_RIGHT:
                    keyboard_hold_right = true;
                    break;
                case SDLK_d:
                    keyboard_hold_right = true;
                    break;

                case SDLK_UP:
                    keyboard_hold_up = true;
                    break;
                case SDLK_w:
                    keyboard_hold_up = true;
                    break;

                case SDLK_DOWN:
                    keyboard_hold_down = true;
                    break;
                case SDLK_s:
                    keyboard_hold_down = true;
                    break;

                
            }
            break;
        case SDL_KEYUP:
            switch (event.key.keysym.sym)
            {
                case SDLK_LEFT:
                    keyboard_hold_left = false;
                    break;
                case SDLK_a:
                    keyboard_hold_left = false;
                    break;

                case SDLK_RIGHT:
                    keyboard_hold_right = false;
                    break;
                case SDLK_d:
                    keyboard_hold_right = false;
                    break;

                case SDLK_UP:
                    keyboard_hold_up = false;
                    break;
                case SDLK_w:
                    keyboard_hold_up = false;
                    break;

                case SDLK_DOWN:
                    keyboard_hold_down = false;
                    break;
                case SDLK_s:
                    keyboard_hold_down = false;
                    break;
            }
            break;

        case SDL_MOUSEMOTION:
            mouse_x = event.motion.x;
            mouse_y = event.motion.y;
            break;
    }
}