These SPDX license identifiers are deprecated ([1]). Update them.

[1] https://spdx.org/licenses/

  sed \
     -e '1 s%^/\* SPDX-License-Identifier: \(GPL-2.0\|LGPL-2.1\)+ \*/$%/* SPDX-License-Identifier: \1-or-later */%' \
     -e '1,2 s%^\(--\|#\|//\) SPDX-License-Identifier: \(GPL-2.0\|LGPL-2.1\)+$%\1 SPDX-License-Identifier: \2-or-later%' \
     -i \
     $(git grep -l SPDX-License-Identifier -- \
         ':(exclude)shared/c-*/' \
         ':(exclude)shared/n-*/' \
         ':(exclude)shared/systemd/src' \
         ':(exclude)src/systemd/src')

Part of !537.

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/537

  $ find * -type f |xargs perl contrib/scripts/spdx.pl
  $ git rm contrib/scripts/spdx.pl

We no longer add these. If you use Emacs, configure it yourself.

Also, due to our "smart-tab" usage the editor anyway does a subpar
job handling our tabs. However, on the upside every user can choose
whatever tab-width he/she prefers. If "smart-tabs" are used properly
(like we do), every tab-width will work.

No manual changes, just ran commands:

    F=($(git grep -l -e '-\*-'))
    sed '1 { /\/\* *-\*-  *[mM]ode.*\*\/$/d }'     -i "${F[@]}"
    sed '1,4 { /^\(#\|--\|dnl\) *-\*- [mM]ode/d }' -i "${F[@]}"

Check remaining lines with:

    git grep -e '-\*-'

The ultimate purpose of this is to cleanup our files and eventually use
SPDX license identifiers. For that, first get rid of the boilerplate lines.

https://bugzilla.gnome.org/show_bug.cgi?id=791121

Update the raw D-Bus python examples to use newer APIs where
appropriate (and split the add-connection example into 1.0-only and
0.9-compatible versions). Update the gi-based python examples for the
various API changes since they were last updated.

Also add a comment to the ruby add-connection example pointing out
that it's still using the old settings APIs.

'has_key' on Dictionaries is removed from Python3 in favor of 'in'.

Signed-off-by: Thomas Haller <thaller@redhat.com>