unfinished Grothendieck construction attempt
Groth: an associativity law proved.
Groth: ugly assoc proof, needs cleanup
Groth: ∘-resp-≡ and smaller assoc proof
Groth: completed! and with nicer proofs.
Groth: renamings
equational reasoning for Congruence.Heterogeneous
Groth: rewrote proofs with HetReasoning
moving ≣-relevant to Categories.Support.Experimental
Categories.Support.Experimental