Rust binding to HdrHistogram_c library.
This is a thin binding to the HdrHistogram_c library
(https://github.com/HdrHistogram/HdrHistogram_c). Aside from the
normal Rust safety features, the main embellishment is an
implementation of the Iterator trait for the various ways to iterate
the histogram.
It also uses `u64` instead of a signed type for values, as the library
does not allow values to be less than 1. However it also means that
any value greater than 2^63 will be treated as negative and rejected.
I've re-implemented the test suite in Rust (cargo test) to exercise
the API, and it all passes.
TODO:
* Finish basic API
* Complete iterator items
* Histogram logging/serialization
* anything missing