New 'slapos-kill' from slapos.toolbox is used instead of 'killpidfromfile'
This is required for NEO which does not write any pid file.

The inline recipe for ERP5 has been improved and converted into recipe,
which is reused for NEO.

Templates are instanciated only if they're used, so no need anymore to
wrap them with:

  {% if slap_software_type == software_type -%}
  ...
  {% endif %}

Move haproxy httpchk configuration per-listen as zope's webdav returns 401
on (at least) GET / . TCP-level checks are still active, which should be
sufficient.
Also, change zope_family_address_list check to getitem as it's more natural
than concatenating.
Also, stop using apache.zope.backend recipe to add support for per-port
scheme so automatic ERP5Site creation knows which URL is really HTTP.
Also, stop using certificate_authority recipe and call openssl directly
when generating self-signed cert for https/webdavs support.
Also, rework balancer parameters a bit (still undocumented).
Also, make instance-balancer always publish ipv6 value (empty when no ipv6
available), so instance-erp5 always succeeds.

Not perfect yet, as some strings end in configuration files for example
and need escape mechanisms aware of individual configuration file syntaxes.

Fixes backend maxconn value: it's now equal to zope's number of threads.
Instead, generate configuration file from template and wrapper from
stand-alone recipe.
One local-only feature is lost: haproxy-ctl command is not present, but its
usage should be rare enough to not be a problem now. Socket is present
anyway, so any tool able to access a unix socket would do (ex: socat).

Also, fix frontend request.

This work has nothing to do in erp5-component branch, and is preventing it
from being merged to erp5 banch more often.
Conflicts because of non-reverted
6d1a9805 have been resolved to that its
intent is preserved with non-cluster ERP5 SR.

This reverts commit 77976a14.
This reverts commit 7aa1d92c.
This reverts commit 80062015.
This reverts commit 36ed58f2.
This reverts commit 1fe3f466.
This reverts commit 7731726a.
This reverts commit eb2016c4.