chashmap: Add support for lookup by borrowed value (mirror HashMap support for Borrow)

See merge request !86

Gosh would someone please kill me. https://twitter.com/ticki_/status/901478579925602304

- Add tests for it and `Guard::new` et al.

Conc: fixed typo in `atomic.rs`.

Signed-off-by: Cooper Paul EdenDay <cedenday@protonmail.com>

Signed-off-by: Cooper Paul EdenDay <cedenday@protonmail.com>

Previously, it was possible to break invariants as some of the API
interfaces didn't respect the trait bounds. This should now be fixed
through requiring respective trait bounds.

- Adjust the settings defaults.
- Add settings prefixes (and add tests for them).
- Set `conc::add_garbage_box()` to `unsafe`.

Disabling GC didn't disable it, because if the generator integer is 0, it GCs, so there is one case where it can indeed GC.

- Semicolons in `atomic-hashmap`

This is a simple thread local variable with a `Settings` struct that contains a bunch of parameters, previously hard-coded into constants. You can update these values.

- Update to the new `conc`.
- Remove the idea of logical insertions/removals.
- Add an ABA loop to `remove`.

- Link blog post.

Update keywords.

It didn't recurse through the destructors.

This does extra printing to stdout, if you set `CONC_DEBUG_MODE`.

Speck: added basic benchmarking.

Speck: added trait derivation for `Key`.

This removes the use of the `Atomic` API to bypass unnecessary destructors. It does however not fix the issue, since some (likely related) bugs are still there.

- Add `add_garbage_box`.

Signed-off-by: Cooper Paul EdenDay <cedenday@protonmail.com>

Signed-off-by: Cooper Paul EdenDay <cedenday@protonmail.com>

Signed-off-by: Cooper Paul EdenDay <cedenday@protonmail.com>

Signed-off-by: Cooper Paul EdenDay <cedenday@protonmail.com>

Signed-off-by: Cooper Paul EdenDay <cedenday@protonmail.com>