Concurrent Map Candidate: chashmap about not-yet-awesome-rust

[ErichDonGubler]

@wezm, @software-is-art: While I don't believe chashmap or flurry fulfill the "hole" documented (having something as close to std::collections::HashMap as possible), I believe dashmap does satisfy the vast majority of the items currently on the NYAR list -- it even states at the beginning of its API docs:

DashMap tries to implement an easy to use API similar to std::collections::HashMap with some slight changes to handle concurrency.

It's been a while since I've looked at this part of the ecosystem, so thanks for the bump! I think I'll close this specifically for dashmap as the solution. I want to recognize your efforts, though I hesitate to add the crates you've suggested only because documentation goes stale, so more content means more potentially out-of-date content later.

[wezm]

Jon Hoo has been working on one too https://github.com/jonhoo/flurry