Make explicit arguments

[moodymudskipper]

unique_x_key = c("ignore", "inform", "warn", "abort")

• Not everybody will like the short form
• long form is more readable for occasional use (no need to remember or check doc)
• when we just want to silence one default, check = "" silences everything and is not easily understood in examples.

check will be NULL and ignored by default and will override all the rest if not NULL.

Doc will need update

[moodymudskipper]

still not sure about this

[moodymudskipper]

Done in {powerjoin}