Order of edges in `.e` and `.class`

[mschauer]

It is a bit confusing that the order of edges in maps.e doesn't respect the order edges(mapx.g) gives.

julia> collect(edges(mapx.g))[100]
Edge 62 => 63

julia> mapx.n[ans.src], mapx.n[ans.dst]
(140183299, 300033881)

julia> mapx.e[100]
(140251695, 140251692)