The reportBuilder assumed we were always processing events for a single
package at a time. This is not true however when running `go test -json
-race` for example. In order to properly support processing events from
different packages we now have packageBuilders per package name.
Fixes#134
The only reason groupBenchmarksByName needed the reportBuilder receiver
was to access its output collector. By passing the output explicitly to
the groupBenchmarksByName function we can remove the reportBuilder
dependency.
The reportBuilder has been updated to use the ordered output collector
to keep track of go test output. This makes it possible to include
benchmark output in the generated report and makes sure that output is
preserved when deleting subtest parents from the report.
Having multiple benchmarks for a single name is something specific to
the gotest output, so grouping benchmarks by name is not something that
belongs in the junit package.
