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Users generally expect that validate Sketch checks the visible part, perhaps because it is not called from the sketcher's edit view, but from the 3D view, perhaps
because that part is relevant for further construction.
On the other hand the tool's name is Validate Sketch and construction geometry belongs to the sketch.
So a new checkbox is introduced, by default enabled to ignore construction, but still allowing the user to make it operate in one direction or the other.
See:
https://forum.freecadweb.org/viewtopic.php?f=3&t=26139&p=208582#p208693
Added buttons to port sketches to CCW-emulation Sketcher.
Bonus =) : Added constraint orientation lock/unlock buttons (affects
point-wise modes of tangent and perpendicular constraints so far)
