Allow redundant parens in comprehension values.

[robsdedude]

Add an exception for redundant parentheses in comprehension value expressions (and key expressions for dict comprehensions) if they are multi-line.

Examples:

[
    (
        item.isoformat()
        if isinstance(item, datetime.datetime)
        else item
    )
    for item in data
]

{
    (
        k
        * SOME_LONG_KEY_MULTIPLIER_NAME_GOES_HERE
        + LONG_NAMES_CAN_BE_ANNOYINGLY_LONG_CANT_THEY
    ): (
        v[0]
        if isinstance(v, list) and len(v) == 1
        else v
    )
    for k, v in otherdict.items()
}

Not however:

(
    (i * 2)
    for i in range(100)
)

Closes: #42