Brasenham alogirthm and draw_on functions philosophy

It is a good idea indeed to have apply_on method inside the
brasenhamalgorithm class, that given a canvas, directly draws the
the result on it. (Not one returning points coordinates and then draw
them on the canvas with another methods and so long).

Also top_left/top_right/bottom_left/bottom_right to return new Points
instances, althouth not quite sure if it is that good of an idea
is hunder times more readable and easily distinguishable for me

Plus fix equality function problems in the Rectangler class I had.
Renderers module and the hierarchy in it - masterpiece for me