MEP 22 update

Hello everybody

I just updated the implmentation part of
https://github.com/matplotlib/matplotlib/wiki/Mep22 to reflect what is
already in place, should be clearer than navigate through the code

The example should be working examples/navigation.py

I know it is confusing, and there are better ways to do many of the
things that I try to do.
Please ask questions, make comments and give your opinion.

For the time being I only implented the changes in GTK3, but if I see
that you are happy with the shape this is going, I will do it for the
other backends (where I know how to do it) and will ask for help
(where I don't know how to do it)

Thanks
Federico

ยทยทยท

--
Y yo que culpa tengo de que ellas se crean todo lo que yo les digo?

-- Antonio Alducin --