Adding an exporter class, allows for exporting the results into different format.
Problem to solve
Current the command line tool export automatically to stdout. This does not allow users to easily parse the result set and display it however they want, for example if someone wants to write automated benchmarking code that tests against different versions of Dart, export the results how they want it. And display it on a site for everyone to see the differences between versions.
Proposal
Create a abstract exporter class, that is able to receive the results sets, and is able to do something with it. And implement a simple stdout exporter for the benchmark tool to use as default.