Add a way to get quantiles from the TestResult.
Use cycle and current_cycle properly.

When you specify cycles, you provide values such as 10:20:30 which means that
you want to have 3 cycles, with 3 different number of tests to run.

In loads, "cycle" is the cycle you are in (10, 20 or 30), whereas current_cycle
is the identifier of the test you're running, that's somehow confusing and
I was actually confused.

Docs needs an update as well.
add an actual gnuplot output
Use all the values in loads_status as the dict key.

Otherwise it's not counting properly.
This commit also moves away from defaultdicts since it was only introducing
fuzzyness.
I see dead code.
don't try to do a .split on lists.