Synchronization of implementations for layers applicable to complexes of arbitrary rank

[georg-bn]

Some simplicial(/cellular) complex layers are applicable to complexes of arbitrary high rank. This raises the question of how the input to these layers should be formatted.

In #129 we use a dictionary each for adjacencies, incidences and features, indexing each adjacency/incidence/feature matrix by their rank. In #142 lists are used instead. I must admit that I have not carefully checked all implementations to see if there are more examples. Perhaps neither of these solutions is robust enough and there should be some custom data structure for a complex, something like an analogue to the SimplicialComplex class in TopoNetX but using PyTorch instead of NumPy?

In any case it would be good to synchronize the implementations, so I started this issue for discussing!