[calib2] Create a task which allow to check control points in rings

[vallsv]

Proposed by Jon Wright, and could fit the request of Fred Picca (allow to provide fit tools with a cake view)

• This task will contains a plot in radial/azimuthal
• With theoretical location of the rings
• Plus a scatter plot with control points
• Providing tools to manage the computed geometry
• Providing tools to manage the control points (remove/ignore some of them, change ring labels)

[vallsv]

Here is the result of my branch https://github.com/vallsv/pyFAI/tree/proto-control-points-task. I don't think there is interesting things to save from that. Except a serious work on it.