highlight stray parenthesis, braces, brackets, quotes, and commas in red

`pretty-simple` currently parses parentheses, braces, brackets, etc to neatly display nested data structures.

It would be nice to have stray parentheses, braces, brackets, etc be highlighted in red so the user could tell they are strange.

For instance, imagine a Haskell data type that has a show instance that looks like the following:

```haskell
Foo { foo1 = 3.3, foo2 = "hello" } }
```

It would be nice if `pretty-simple` highlighted the last `}` in red so the user could see that something is strange.