Turn _compute_arguments into a function.
Add a TestResult adapter, consuming extra args.

Otherwise it fails when we give extra information to the default unittest
TestResult implementation.
Add some comments to make things clearer.
Pass a data_type argument when we push the streams.

This helps to keep track what is the kind of data that's passed, so no guess
need to be done by looking at its arguments.
Pass information about cycles to the session.

This allow to keep track of the cycles concerned in the streamers.
Add a StreamCollector class.

The StreamCollector is a stream class, but collects all the data with the goal
to make it easily queriable.

That is the first building block of a report system. One can read this object
in order to create reports easily.
Enhance docstrings of the runner.py module.
Plug the StreamReader with the runner.
PEP 8
Pass "total" rather than "stream_stdout_total".

The rationale behind this choice is to allow any streamer to get a number of
options that are valid for the hole run. "total" is one of them, but some other
ones can be used as well.
Use the new "data_type" arg when streaming data.