allow shortcut begin end syntax inside match and if then else

[EmileTrotignon]

Instead of

match () with
| () -> begin
    match () with
    | () ->
  end
end

you get

match () with
| () ->
    begin match () with
    | () ->
    end
end

Same thing with if-then-else

[Julow]

This is an other large change to the formatting of begin .. end. I think we should let the community debate and vote for a formatting that will stay for a while.
Or perhaps, this should be behind an option ?

[Julow]

I think "allow" here is ambiguous. Do you change the formatting for everyone or is here an other allowed formatting ?

[EmileTrotignon]

I change it everywhere, use would be better

[EmileTrotignon]

We can make a topic on discuss, I would rather not introduce a new option.

[EmileTrotignon]

Another thing to point regarding making "big changes" is that after releasing 0.28, we had some negative feedback, but all of it was about bugs/regressions, none of it was people complaining about the intended changes. So I think the reception was clearly positive.

[EmileTrotignon]

Discuss poll here

[EmileTrotignon]

Results of the poll are clearly in favour of the change

[Julow]

Awesome :)

Can you fix the conflicts and merge ?

[EmileTrotignon]

This is not great but should be fixed by #2745