Added `graphics/SpriteBatch` header with `SpriteBatch` class
in `graphics::SpriteBatch`:
  - added abstract `begin()`
  - added abstract `end()`
  - added abstract `backgroundColor() -> Color` getter
  - added abstract `backgroundColor(Color)` setter
In `graphics::SpriteBatch`:
  - added `Drawer` structure
  - added abstract `draw() -> Drawer`
Included `Color` header;
Added empty definition of `SpriteBatch::Drawer` structure
Added bunch of headers;
In `graphics::SpriteBatch::Drawer`:
  - added abstract `texture(texture, position, rectangle, angle, center)`
In `graphics::SpriteBatch::Drawer`:
  - added abstract `texture(texture, position, angle, center)`
In `graphics::SpriteBatch::Drawer`:
  - added abstract `quad(rectangle, color)`;
  - added abstract `point(p1, p2, color)`