Emacs object type hierarchy

[Andrea Corallo]

Hello all,

for some develepment I need to have the type hierarchy definition,
something more detailed compared to what we have now in
`cl--typeof-types` (see bug#66615).  Because of that I've been trying to
reconstruct the type hierarchy of Emacs objects before coding it in.

So far this [1] is where I'm arrived at.

Do you spot any error? Any comment welcome.

Also I think we might want to document it with something similar in the
manual in the future WDYT?

Thanks

  Andrea

[1] 
<https://gitlab.com/koral/emacs-type-hierarchy/-/blob/master/h.dot.png?ref_type=heads>