The Amount related Denomination struct parses to and from strings. Currently it uses the plural for Denomination::Bit and the singular for Denomination::Satoshi.

We should be uniform, either we support singular, plural, or both for all the abbreviation denominations (bits and sats).

1. let a = Amount::from_str("100 bits") and let a = Amount::from_str("100 sats")
2. let a = Amount::from_str("100 bit") and let a = Amount::from_str("100 sat")
3. Both 1 and 2

For reference, here is the from_str implementation.

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "BTC" => Ok(Denomination::Bitcoin),
            "mBTC" => Ok(Denomination::MilliBitcoin),
            "uBTC" => Ok(Denomination::MicroBitcoin),
            "bits" => Ok(Denomination::Bit),
            "satoshi" => Ok(Denomination::Satoshi),
            "sat" => Ok(Denomination::Satoshi),
            "msat" => Ok(Denomination::MilliSatoshi),
            d => Err(ParseAmountError::UnknownDenomination(d.to_owned())),
        }
    }

Found while testing #509