Add delay coordinate embeddings

[WolfByttner]

Delay coordinate embeddings are a technique for visualising time series. You compute a mapping, (x(t), x(t+k)), where k > 0 is an offset. This gives you a 2-d graph that represents the trajectory as a figure (technically it is close to a topological tangle). This can then be used to compute (for instance) the homology (with mapper, or the persistent homology) of the trajectory.

[WolfByttner]

Some visualisations:

https://coledie.com/DelayCoordinateEmbeddings

I should point out that relevant code exists in notebooks and we need to port it to Traja.