Add DALI XY

[nikosarcevic]

Brainstorming idea: we should explore the generalized fisher as it mentioned DALI can be done in the same manner.
I think Matthijs was interested in giving it a go. @lonbar @ctrendafilova
Feel free to discuss, ref paper linked here.

[nikosarcevic]

Also my understnding is that we currntly can already do DALI with param dependent cov (I am not sure if we tested this tho)