0028764: [Regression to 7.0] Intersection of faces gives exception in debug mode

0028764: [Regression to 7.0] Intersection of faces gives exception in debug mode

Some point were incorrectly removed from the Walking-line.

In the current fix, new method IntWalk_PWalking::RemoveAPoint(...) has been added and implemented in order to provide safe removing.

So, now methods AddAPoint(...) and RemoveAPoint(...) are recommended to use for work with the Walking-line.