Implement schemars::JsonSchema for new types.

[gibbz00]

Placed behind a schemars feature flag.

[ramosbugs]

I wasn't familiar with schemars, but it seems popular enough that this is worth merging. Still, I wonder if it's worth waiting for their 1.0 release (GREsau/schemars#290) since bumping the schemars dependency would be a breaking change. Though, as long as schemars 1.0 is API-compatible (for the subset of APIs used by this crate), we could also just change Cargo.toml to schemars = { version = "0.8, 1", optional = true } once 1.0 is released without introducing a breaking change. Thoughts?

[gibbz00]

Hey again,

Apologies for the late reply, got a lot going on at work...

Still, I wonder if it's worth waiting for their 1.0 release (GREsau/schemars#290) since bumping the schemars dependency would be a breaking change.

Good point. I think that the safest and easiest way forward it to simply wait for the 1.0 release. It seems to be just around the corner, and I'm not in too much of a hurry 😊