Do it while parsing, so (for example) day splitting happens at midnight in
chosen timezone instead of midnight in source timezone.
When no timezone is provided, use input's times verbatim.
DST changes cause artefacts in graphs (double or zeroed hour).
Also, display used timezone in generated page.

Depending on input, some state files can starts with ".", and are not
matched by "state/*".

Turns out, builtin works fine with shlex with python 3.

Allows shell expansion (ex: "@~/foo.cfg" cannot be expanded, "@ ~/foo.cfg"
can be).

Replace with quarterhour, do not change plot period.

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.