Incorrect pretty printing for types

[brianhuffman]

Here's an example type error message that prints a type constraint with not enough parentheses:

Cryptol> :t (zero : Float 2 3) <$ zero

[error] at <interactive>:1:1--1:27:
  Unsolved constraints:
    • SignedCmp Float 2 3
        arising from
        use of expression (<$)
        at <interactive>:1:1--1:27
[error] at <interactive>:1:2--1:18:
  Unsolved constraints:
    • ValidFloat 2 3
        arising from
        use of partial type function Float
        at <interactive>:1:2--1:18

In particular, the line containing SignedCmp Float 2 3 is missing some parens; it should print as SignedCmp (Float 2 3).