Links between slices and between layers

A slice corresponds to a machining path at the same altitude.

A layer corresponds to a machining altitude.

The following link modes are available ;

	Direct line The link is made by a straight segment
	Feed distance The link is made with an upward movement along the tool axis at the distance and then by a direct straight line link. The ascent altitude is defined by the value "Entry feed distance" for the approach and by the value "Exit feed distance" for the retract.
	Clearance The link is made at the level of the form of security (cylinder or sphere). The tool retracts along its axis until it reaches the safety shape. In the case of a "flat" impeller (axial blade axis) with a cylinder type shape, the tool axis is almost aligned with the cylinder axis, the movement will be very long in the centre of the safety cylinder.
	Blend spline The link is done by a spline tangent curve.
	Direct blend This type of link is a combination of direct link and spline curves . Eventually it should definitively replace the spline curve.Indeed it limits the link length and the distance from the finish.