More compact `show` method when compact=true

Current behavior when `show`ing in compact mode is:
```julia
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
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 `OpenInterval`s:
```julia
julia> show(IOContext(stdout, :compact=>true), MIME("text/plain"), OpenInterval(a, b))
0.320888..0.57142(open)
```