switch from time to systemtime

[esheppa]

This reduces a dependency, but also makes ulid compatible with all datetime libraries as the internal types generally implement From<SystemTime>.

This should also solve #52 and potentially #50

[dylanhart]

Hi Eric! Thank you for you contribution. Currently the PR is not compiling:

$ cargo test
   Compiling ulid v0.6.0
error[E0433]: failed to resolve: use of undeclared type `Duration`
   --> src\generator.rs:182:46
    |
182 |         let ulid3 = Ulid::from_datetime(dt + Duration::from_millis(1));
    |                                              ^^^^^^^^ not found in this sc
ope
    |
help: consider importing one of these items
    |
174 |     use core::time::Duration;
    |
174 |     use std::time::Duration;
    |

For more information about this error, try `rustc --explain E0433`.
error: could not compile `ulid` due to previous error
warning: build failed, waiting for other jobs to finish...

Can you fix the issues? The following should all pass:

cargo test
cargo test --all-features
cargo test --no-default-features --features=std
cargo test --no-default-features

Thanks!

[esheppa]

Thanks for the review @dylanhart - I've fixed the compile error and verified with the cargo test commands you listed. I also fixed the cli which I'd broken due to SystemTime not implementing Display, so I've added that to the CI checks as well

[dylanhart]

Hi Eric! Thanks for the update. Can you remove the panicking .unwrap() calls? Thanks!

[esheppa]

Thanks @dylanhart - I've fixed those unwrap calls - let me know if you are ok with the additional wording in the docs

[dylanhart]

This looks great. The code and rustdoc look good to me. Just one comment on cargo features.

[esheppa]

I've cleaned up the Cargo.toml and README.md. I've left the benchmarks as is as I assume you'd like to run them on your computer for consistency

[dylanhart]

Looks good! Thanks! Will make a release for this later.

[dylanhart]

Available in v1.0.0