Eaf

Simple Timer class for tracking time.
Update it like any other object within State.update(dt) method.

* Now all interactions between Renderer and Renderable are passed to Image subclasses.
* 'get_render_data()' and 'draw_on_border' things were removed from Renderable.

Finally we have some breaking changes!
* all useful things are provided on eaf package level
* added Application.frame_count property
* added simple clock implementation and used for calculating the delta between frames
* delta passed to State.update and to it's objects
* made initial steps for implementing configurable FPS during runtime

Fix formatting.

Add Singleton metaclass.

Small non-breaking additions to render module