Unlike apache which escape non ascii characters in referrer, caddy
writes referrer as is. Edge seem to send referrer not escaped, so with
Edge and caddy we can have non ascii text in referrer.

For lines which cannot be decoded as ASCII, we use python `replace`
error handler which would in this case allow the line to be processed if
the decoding problem is only about the encoding of the referrer.

We don't implement this case as "skip and report ill-formed line",
because python does not provide utilities to do this easily.

Reproduction with caddy:

```
curl -k http://localhost -H 'Referer: héhé'
```

With apache, `LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\"" common`
```
127.0.0.1 - - [28/Feb/2019:10:03:33 +0100] "GET / HTTP/1.1" 200 2046 "h\xc3\xa9h\xc3\xa9" "curl/7.50.1" 4
```

With caddy, `log / stdout "{remote} {>REMOTE_USER} [{when}] \"{method} {uri} {proto}\" {status} {size} \"{>Referer}\" \"{>User-Agent}\" {latency_ms}"`

```
127.0.0.1 - [28/Feb/2019:10:05:00 +0100] "GET / HTTP/2.0" 200 1950 "héhé" "curl/7.50.1" 4
```

When the table is large and requires scrolling, it becomes difficult
to read so add 'title' attribute to <tr> on 'Stats per module' and
'Hits per status code' tables. For example when hovering a particular
cell on a module row, it display the module name.

/reviewed-on !3

We observed lines in our logs where the timestamp field was still
respecting the timestamp regexp, so the line was not reported as
invalid, but parsing such timestamp caused a ValueError in
_matchToDateTime

The beginning of line was:
127.0.0.1 - - [14/Jul/2017:127.0.0.1 - - [14/Jul/2017:09:41:41 +0200]

Which uses `[14/Jul/2017:127.0.0.1 - - [14/Jul/2017:09:41:41 +0200]` as
timestamp, so this fail the simple .split() used to separate timestamp
and timezone.

Added a minimal test case to reproduce this specific problem.

Use a decorator to not indent the whole function.

This change introduces a (minor) parameter value backward-incompatibility.

There is no standard unquoted URL encoding (=charset), so do not unquote
to just handle ASCII. Fixes various UnicodeDecodeError failures, at the
cost of decreased report readability.

This causes errors and solves nothing.

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.