Extend mixing factors to more sequences

[jusack]

This PR adds the possibility to calculate mixing orders from N frequencies, covering all types of trajectories (Lissajous, FFL, etc)

The following parts are still open:

• Check if calcPrefactors is correct Check definition of prefactors/mixing orders #128
• Decide if custom MDF component is the way to go for irregular mixing factors or if the MDF standard can be extended in a more flexible way
• Document breaking change (mixingFactors is no longer Fx4 but Fx(N+1)
• Maybe name the mixing factors, to add information in visualizations