http_clnt: document treatment of multiple headers with same name
FAQ: fix links
FAQ: remove unrecognized admonitions
runner_hosts.py: sync
www/header.html: more precise copyright statement

Don't mention Universita` degli Studi di Milano, since Alessio
work on Neubot is not related with such university at all.

He worked on Neubot in his free time, and his academic activity
was on a completely different topic.
http/message.py: disable prettyprint of body

Dash noticed that this feature was too slow in certain cases (e.g., big
JSON messages).

To make sure this feature does not harm, comment it out. I will uncomment
this feature when I need it to debug Neubot.
api_results.py js/results.js: rewrite for clarity and flexibility

The new code is more easily readable (and documented by results.js.dia,
results.js.png and results.js.svg in doc/neubot).

The new code is more flexible because now you don't need to restart
Neubot to add a new test. Moreover, it allows power users to heavily
customize the presentation of results (via files in www/test).

I also have added more www_FOO options to allow ordinary users to
customize the presentation of results as well.

The core change is a new /api/results JSON format that more clearly
specifies how to construct the results table and charts.

Notably, the static list of available tests in results.html is now gone
- forever.
results.js: use lisp-like code to customize plots

Allows you to specify how to process results and effectively removes
the need to have a common format for every test.

Solves an issue raised by Dash Elhauge when he was doing an intern
here at the Nexa Center.
results.js results.html: plot appearance improvements

1. create less high plots, so they occupy less screen estate
   on netbooks and other small screen devices;

2. move style from style.css to jquery.jqplot.css: there is
   no need to create more confusion, since the latter css file
   is under git (so, I'm not afraid by future merges);

3. better legend position; also, enable more interesting
   plugins, like cursor tootip and highlighter;

4. commit commented-out code to have logscale axes: this is
   still work in progress and won't be in next release;

5. better solution for when there is no data to plot: provide
   a vector that forces jqplot to create empty charts;

6. better code to select x axis format depending on the
   selected time interval;

7. add the plugin needed by point 4. above.
www: don't mention version number in footer

Avoids bugs, like the version number being old in the italian
translation of Neubot.
utils_posix: review the code, fix bugs, improve unit test
utils_posix: add the possibility of using a logfile
utils_posix: simplify interface to daemonize and propagate changes

The interface to daemonize, detach(), was complex and, hence, error
prone. I replaced it with a simpler interface and propagated changes
to neubot/system_posix.py.
updater/unix.py: use utils_posix
updater/unix.py: allow to choose nonpriv user for updates
agent.py: honor /etc/neubot/users
updater/unix.py: don't unconditionally append to sys.path
utils_posix.py: make sure we create pidfile with standard umask
js/results.js: be robust when raw's web100_snap is {}

Since {} is the default value for previous versions of Neubot, the
code should be able to deal with it correctly.

To verify this diff works, I temporarily modified the raw test
to store {} (instead of []) in the web100_snap field.
test/raw.json: disable average-cwnd and plr plots

In the next release of Neubot, we are not yet ready for this
two plots. I will revert this patch after the release.