Location of Kirchhoff lift CNf peak is discretized due to added mass noise

[lucasschn]

Noise related to added mass is making the CNf = CNk+CNI curve wobbly, which in turn makes the location of the maximum CNf wrongly identified to a noise peak.

In turn, the scatter plot with all peak locations is discretized.

[lucasschn]

After using smooth derivatives algorithm the result is better