Ensures connectivity of curves, for example in a composite curve.
Implementations should ensure at least 0th order continuity, which means that for two consecutive curves,
the end point of the first will coincide with the start point of the second.
The slopes of the curves may differ at the connections.
(Re)connects a curve to the given previous and next curve.
In other words, aCurveSFCT will be modified so that its start point
will coincide with the end point of aPreviousCurve, and its end point
will coincide with the start point of aNextCurve.
Either of aPreviousCurve or aNextCurve can be null, but not both.
aPreviousCurve - the previous curve. Will not be changed. Can be null.
aCurveSFCT - the curve whose start and end point should coincide with
aPreviousCurve's end point and aNextCurve's start point, respectively
aNextCurve - the next curve. Will not be changed. Can be null.
aModelReference - the model reference of the given curves