This reverts commit ef5aca54.

software-shared.cfg is used on master from scalability tests, let's keep
it for now.

Install setuptools_scm before jsonschema (which has it in setup_requires) so that the version can be controlled by buildout

See merge request !768

We don't need a section here, we inherit this from jupyter stack

See merge request !756

Since e5687602 it's instance
responsability to generate a fonts.conf if they need fonts, but we
realized to late that if there is no /etc/fonts/fonts.conf on the
machine firefox does not start.

In recent ERP5 software release, we have a $FONTCONFIG_FILE, but on
older versions we don't.

To keep compatibility with old ERP5 software release, we generate a
default FONTCONFIG_FILE that will be used as fallback when
$FONTCONFIG_FILE environment variable is not set.

As we have kvm with a section deployed using
collective.recipe.shelloutput, if collective.recipe.shelloutput isn't in
the SR folder anymore this section can't be uninstalled (as the
uninstall method is defined in the egg).

The output of buildout for this error was :

Installing switch_softwaretype.
Uninstalling frontend-port.
While:
  Installing.
  Uninstalling frontend-port.
  Installing recipe collective.recipe.shelloutput.
  Getting distribution for 'collective.recipe.shelloutput'.
Error: We don't have a distribution for collective.recipe.shelloutput
and can't install one in offline (no-install) mode.

The cause was a7a36453

See merge request !700

now that we have a patch to support gcc 8 we should support all known
versions of gcc

gcc-5.5 compiles a bit slower python and we are observing failures in
ERP5 performance tests.