Drop most deprecated code in cubicweb.web
This includes both Python and JavaScript code. Most code has been
deprecated since a very long time (versions 3.1x mostly, more than 5
years ago, and a few things until 3.24).
There are still a few deprecated things, most of which are actually used
within cubicweb (or in cubes we depend on for tests). I don't know what
to do with these...
Removed a couple of unused imports along the way.
Changelog entry will come in a later changeset.
etc/init.d
etc/cubicweb.d
etc/bash_completion.d
usr/bin
usr/share/doc/cubicweb-ctl
var/log/cubicweb
var/lib/cubicweb/backup
var/lib/cubicweb/instances