Closed in favor of#2759

This is the first draft for the MEP22,

The idea is just to lookat the new organization of stuff. The documentation will come later I promise.
The only backend working is GTK3, everything else is broken

Just one example for the momentexamples/user_interfaces/navigation.py

For implementation structurehttps://github.com/matplotlib/matplotlib/wiki/Mep22#implementation

For the version that keeps the NavigationToolbar classes#2759