Feature request: Simulated REPL sesstion for markdown output

[pdeffebach]

I would like something like the following

1 + 1
3 + 4

to get translated as

julia> 1 + 1
2

julia> 3 + 4
7

And also respect :compact text printing of arrays and data frames.

I imagine this is difficult to do. So no pressure. But it would be nice to do, in general.