added initial
started pullbacks
pullbacks contd
updated gitignore
changed order of fiber_path and fiber_path_UU for consistency
changed order of total_path_reconstr and ..._UU for consistency
commented out some useless lemmas
some cleanup in aux
removed some functions that were commented out
made some proofs transparent, simplifying some subsequent proofs for inverses of morphisms
removed commented proof code
transparent inverse under functor application
profit from more convertibility
some streamlining in functors
transparented a proof in equivalences
added terminal
started topos stuff
delete useless hProp instance
started lemmas about transportf in sigmas
added aux_lemmas to Make