Steps to verify the issue:
1. Open FreeCAD.
2. Switch to Std_ViewTop.
3. Click one of the curved arrows of the Navigation Cube.
4. Switch to the Draft WB.
5. Make sure Draft_SelectPlane is set to "Auto".
6. Start Draft_Arc and click 2 points (for the radius and the start angle).
7. Result: The displayed arc does not match the start angle or the current point.
Additonally:
* Removed the normal argument from `__init__`. The tracker does not work properly with just a normal. AFAICT there is no code that specifies this normal.
* Minor improvement to `getAngle`: Switched the vectors.
65cd8adca8