Sketcher: Axes visualization improvement
Sketcher: Axes visualization improvement

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Axes size was bounded to the boundingbox of the underlaying 2D shape. However, this does not even get updated in no update mode and provides unreliable values.

The axes calculation now:
- is coded to be the same size and fully symmetric.
- is coded to be minimum 100 mm semiaxis, which gives a good impresion for empty sketches with default zoom.
- is coded to grow with the largest of the semiaxes.

fixes #3334

Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master