Merge branch 'bottine/simple_graph/ends_for_real_this_time' of https://github.com/leanprover-community/mathlib into bottine/simple_graph/ends_for_real_this_time
Merge branch 'bottine/simple_graph/ends_for_real_this_time' of ssh://github.com/leanprover-community/mathlib into bottine/simple_graph/ends_for_real_this_time
Merge branch 'bottine/simple_graph.ends/Freudenthal_Hopf' of ssh://github.com/leanprover-community/mathlib into bottine/simple_graph.ends/Freudenthal_Hopf