add --compact switch to the pretty-simple executable

[juhp]

This is towards #34 adding a --compact cli option.

[cdepillabout]

This looks good to me!

$ pretty-simple --compact
{ "hello" = [ "now", "bad" ], tomorrow = Just (3, 4) }^D
{ "hello" = [ "now", "bad"  ], tomorrow = Just ( 3, 4 )  }
$ pretty-simple
{ "hello" = [ "now", "bad" ], tomorrow = Just (3, 4) }^D
{ "hello" =
    [ "now"
    , "bad"
    ]
, tomorrow = Just
    ( 3
    , 4
    )
}

[cdepillabout]

@georgefst @juhp Want me to do a release?

[georgefst]

@georgefst @juhp Want me to do a release?

Go for it, thanks!

I've just merged #104, which gives us one more reason to release.