Implement quasi-static tether model for KPS3 and KPS4

[ufechner7]

Would be interesting to see the effect of such a model on

• the power output
• the max force
• the performance

TODO:

• Add parameter quasi-static in KiteUtils to the section tether
• take it into account when calculating the dynamic particle forces

[1-Bart-1]

I guess it isn't very difficult to set the residual directly to the acceleration, and that will result in a quasi-static model?

[ufechner7]

It should be easy, yes. But you need tests, a new configuration parameter etc, so it is also some work.