stdlib: Add newline before `pre` if not done by `p`
stdlib: Add newline before `pre` if not done by `p`

When the following is rendered:

    [<<"foo">>,{pre,[],[<<"bar">>]}]

The old behaviour only inserted one new-line which causes it
to look like this:

    foo
       pre

instead of:

    foo

       pre

which is what you want.

rlipscombe/otp,erlang/otp,g-andrade/otp,erlang/otp,mikpe/otp,dgud/otp,uabboli/otp,mikpe/otp,getong/otp,getong/otp,ferd/otp,g-andrade/otp,jj1bdx/otp,jj1bdx/otp,potatosalad/otp,g-andrade/otp,isvilen/otp,ferd/otp,getong/otp,ferd/otp,dgud/otp,getong/otp,dumbbell/otp,vinoski/otp,isvilen/otp,uabboli/otp,getong/otp,dgud/otp,jj1bdx/otp,jj1bdx/otp,rlipscombe/otp,bjorng/otp,uabboli/otp,ferd/otp,erlang/otp,dgud/otp,erlang/otp,dgud/otp,dumbbell/otp,rlipscombe/otp,emacsmirror/erlang,mikpe/otp,emacsmirror/erlang,ferd/otp,bjorng/otp,getong/otp,erlang/otp,isvilen/otp,vladdu/otp,potatosalad/otp,lrascao/otp,bjorng/otp,emacsmirror/erlang,bjorng/otp,isvilen/otp,dumbbell/otp,g-andrade/otp,emacsmirror/erlang,emacsmirror/erlang,bjorng/otp,ferd/otp,uabboli/otp,vladdu/otp,lrascao/otp,vinoski/otp,uabboli/otp,g-andrade/otp,emacsmirror/erlang,lrascao/otp,vinoski/otp,ferd/otp,emacsmirror/erlang,potatosalad/otp,ferd/otp,dumbbell/otp,jj1bdx/otp,isvilen/otp,dgud/otp,ferd/otp,potatosalad/otp,dumbbell/otp,dgud/otp,getong/otp,jj1bdx/otp,isvilen/otp,dgud/otp,uabboli/otp,getong/otp,isvilen/otp,g-andrade/otp,vinoski/otp,isvilen/otp,vinoski/otp,rlipscombe/otp,dumbbell/otp,uabboli/otp,rlipscombe/otp,rlipscombe/otp,vinoski/otp,vladdu/otp,uabboli/otp,jj1bdx/otp,potatosalad/otp,erlang/otp,erlang/otp,uabboli/otp,vladdu/otp,mikpe/otp,vladdu/otp,lrascao/otp,vinoski/otp,rlipscombe/otp,lrascao/otp,erlang/otp,potatosalad/otp,erlang/otp,mikpe/otp,vladdu/otp,vladdu/otp,rlipscombe/otp,mikpe/otp,vladdu/otp,g-andrade/otp,erlang/otp,mikpe/otp,potatosalad/otp,lrascao/otp,rlipscombe/otp,emacsmirror/erlang,isvilen/otp,lrascao/otp,jj1bdx/otp,isvilen/otp,vinoski/otp,getong/otp,dgud/otp,potatosalad/otp,bjorng/otp,vinoski/otp,mikpe/otp,rlipscombe/otp,dumbbell/otp,g-andrade/otp,dumbbell/otp,mikpe/otp,g-andrade/otp,potatosalad/otp,dgud/otp,emacsmirror/erlang,vinoski/otp,potatosalad/otp,dumbbell/otp,getong/otp,bjorng/otp,lrascao/otp,mikpe/otp,g-andrade/otp,bjorng/otp,jj1bdx/otp,jj1bdx/otp,bjorng/otp,bjorng/otp,dumbbell/otp,lrascao/otp,emacsmirror/erlang,vladdu/otp