Refactor Scatter plot

[Tanguylo]

Full refactor of Scatter plot with new Frame plot as parent class.

New Scatter plot must:

• Draw points with mouse interactions
• Cluster points along zoom box (optional)
• Draw selection window in place of rubberbands
• Custom rubberbands on axis so that they look nice
• Interact with other Frames nicely in multiplot:
  - [x] selection window
  - [x] mouse over / click styles
• Interact with old PlotData objects in multiplot
• Allow to use functions as it was possible with former scatter plot
• Allow to do this in debug mode (draw buttons)
• Work nicely with frontend applications
• Handle points sets and former family points
• Draw points tooltip
• Get a well designed behavior for tooltips
• Implement Graph2D