tracing-honeycomb 0.3.0

Changes

• Full rework of TraceId.
  • Allows TraceIds to be any arbitrary string, as the honeycomb ecosystem expects.
  • Adds many ways of converting to and from TraceIds.
• Rework of SpanId.
  • Instance Ids have been removed, as they are unnecessary.
  • SpanId serialization formatting is now in hexadecimal.
• Changed to send duration_ms as an f64, as honeycomb expects.
  • This allows for sub-millisecond span timing.

Additions

• Trace-level sampling.
• parking_lot feature.

Fixes

• Fixes a deadlock where libhoney's reponses channel was not being consumed.
  • See 9dd18b55ea for much more information.
• Always sends traces if no sampling is set.
• Sampling is now deterministic for a given TraceId.
• Properly set the timestamp field in libhoney.
• Relaxed dependency constraints.

(These were also included in the 0.2.0-eaze.X versions.)