Implement std::error::Error for winrt::Error

[frewsxcv]

Thoughts on implementing the primary Rust error trait for winrt's error type?

[Boddlnagg]

I think I haven't done that so far because std::error::Error has some deficiencies (which is why https://github.com/rust-lang-nursery/failure is a thing). I'm not sure if we are able to support both. Maybe with a feature flag?

[frewsxcv]

I think I haven't done that so far because std::error::Error has some deficiencies (which is why https://github.com/rust-lang-nursery/failure is a thing)

It has some deficiencies, yeah, but this RFC was approved which plans to improve it. This is your crate though, so up to you!