More compact `show` method when compact=true

[sethaxen]

Current behavior when showing in compact mode is:

julia> a, b = sort(randn(2));
julia> show(stdout, MIME("text/plain"), a)
0.320887685039538
julia> show(stdout, MIME("text/plain"), a..b)
0.320887685039538 .. 0.5714203688563335
julia> show(IOContext(stdout, :compact=>true), MIME("text/plain"), a)
0.320888
julia> show(IOContext(stdout, :compact=>true), MIME("text/plain"), a..b)
0.320888 .. 0.57142

This is great, only for the last case, I wish the spaces before and after the .. were eliminated, so that we would instead have

julia> show(IOContext(stdout, :compact=>true), MIME("text/plain"), a..b)
0.320888..0.57142

Similarly, I would want spaces eliminated for compact printing of OpenIntervals:

julia> show(IOContext(stdout, :compact=>true), MIME("text/plain"), OpenInterval(a, b))
0.320888..0.57142(open)