Makes error plot more readable when there are very few errors.

So apdex score impact of errors vs. slowness can be easily estimated.

Costs 30% performance on pypy.

Nothing to convert now - just to avoid future breakage.

data_dict is not modified in loop.

Use a Counter instance from the beginning to factorise identical referrers.
Simplify code used to render error detail to HTML.

Otherwise getNextPeriod will fail if earliest_date is in a different
format.
And one more minor release !

Bugfix release for 1.3 .

Those are really calendar weeks (although starting on monday independently
from locale) as it is less expensive to compute them accurately for table
precision than for graph precision (much fewer dates to convert).

Default behaviour doesn't change.
If --fixed-yrange is provided with a negative value (default), ymax is
left floating.
If --fixed-yrange is provided with a value, ymax is fixed at that value.