Span duration histogram and other improvements to tracing

Axiom adds a span duration histogram and other improvements to tracing.

The span duration histogram gives you a quick overview about the duration of individual spans within a trace. This histogram appears to the right of the waterfall view of traces. The span duration histogram can be useful in the following cases, among others:

• You look at a trace or an individual span and you only know its duration. There is no obvious error. You want to know if you are looking at something normal in terms of duration, or an outlier. The histogram helps you determine if you are looking at an outlier and might drill down further.
• You've found an outlier. You want to investigate and look at other outliers. The histogram shows you what the baseline is and what is not normal in terms of duration. You want to filter for the outliers and see what they have in common.

This release further improves tracing in the following ways:

• Adds support for deep linking to individual span inside a trace.
• Adds support for expanding multiple span events.
• Adds support to export traces in Axiom and Jaeger format.
• Improves the design of the trace waterfall view. With tighter data density, you can scan more spans efficiently.
• Improves the background contrast on span hover and click for readability.
• Changes search across spans so that it is now case insensitive.
• Fixes an issue where missing spans were duplicated if they had multiple children.
• Fixes an issue where child spans were displayed larger than their parent span due to rounding.

In addition, this release fixes an issue where the Grafana data source plugin couldn't query data from Axiom.

To explore the new tracing features such as the span duration histogram, go to the Axiom Playground and click a trace in the list.