Allow multiple plugin names.

Next to specifying plugin names a a single colon separated plugin name
list also allow to specify multiple lines with plugin names with one or
more names.
Make comment somewhat more understandable.
Don't let sd and dir python plugins setup signalhandlers.

Just as we already did in the python-fd use Py_InitializeEx(0)
Add missing config printing for new audit events configtype.
be more precise why files are in the public-domain

As per [1], "License: public-domain" needs an explanation why the work
is in the public-domain.

[1] https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/

Signed-off-by: Marco van Wieringen <marco.van.wieringen@bareos.com>
print_config: check if resource it used at all

prevents a segfault on director, when running with debug >= 900

Signed-off-by: Marco van Wieringen <marco.van.wieringen@bareos.com>