- Update DOSBox Staging Team copyright span to year 2021 (DOSBox Team
copyrights left untouched).
- Add DOSBox Staging Team copyright line to files we extensively
modified throughout 2020 (we add our copyright lines when number of
non-trivially modified lines gets close to 50%).
- Change "dosbox-staging team" to "DOSBox Staging Team", in line with
updated branding.
- Change MAME license identifiers to SPDX license identifiers.
- Cleanup some excessive whitespace around copyright statements.
- Do few adjustments to include order.
- Add few missing copyright identifiers (GPL-2.0-or-later,
LGPL-2.1-or-later, BSD-3-Clause) as appropriate for specific file.
- Move SPDX identifiers to the top in scripts for consistency with other
source files.
- Remove old copy of GPL2 license in italian from old translations.
