implement std::ops::Neg for Decimal

[snd]

the following code fails to compile:

let x = dec!(7314);
let y = -x;

with error:

40 |     let y = -x;
   |             ^^ cannot apply unary operator `-`
   |
   = note: an implementation of `std::ops::Neg` might be missing for `rust_decimal::Decimal`

do you want std::ops::Neg implemented? then i'd do so and open a PR : )

[paupino]

That sounds super useful; thank you!

[snd]

just started implementation when i found this already exists. though only on master and not the latest version (0.8.1) released on crates. maybe time to release a new version?