Re-do all embeddings based on `genembed`

[Datseris]

With the latest addition of genembed, there is framework to do any kind of embedding imaginable, and the need for MTDelayEmbedding, DelayEmbedding does not exist anymore.

This will dramatically reduce source code complexity, but one has to check performance. Also, how to do the weighted embedding in this scenario.

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[Datseris]

Well, it is trivial to do weighted embedding in this scenario, just make one more struct WeightedDelayEmbedding.

[Datseris]

Make a DelayEmbedding(τ::Int, d::Int) function as well for convenience. It should error of d <= 1.

[Datseris]

(I have improved this interface ages ago!)