use SPDX license identifiers and make JFlex "REUSE" compliant

[lsf37]

SPDX is a good way to keep track of which licenses are being used in a project and I think it would make sense to use them consistently in JFLex -- for ourselves, but also to enable others to check licenses automatically. @regisd has already started using them in new parts of the repo, and I think that's great, we should do that everywhere.

More concretely, I'd propose:

• for files that we wrote and own the copyright on, replace most of the copyright header with:
  • one or more copyright lines (authors)
  • one SPDX-License-Identifier line
  • this would remove the VERSION comment on java files, but we have that in javadoc almost everywhere now, so removing it removes duplication
• for 3rd-party files, leave the copyright header as is, but add an SPDX-License-Identifier line as a separate comment.
• for all files that are not commentable, use a dep5 file that lists license and copyright
• review our own documentation files and put those under CC-BY-SA-4.0 if we haven't already done so
• use resue lint (see http://github.com/reuse-tool) to check coverage
• include reuse lint in CI

[lsf37]

@regisd, @sarowe would you be happy for me to go ahead with this?

[sarowe]

+1 LGTM

On Mar 6, 2020, at 7:43 PM, Gerwin Klein [email protected] wrote:

@regisd https://github.com/regisd, @sarowe https://github.com/sarowe would you be happy for me to go ahead with this?

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[regisd]

+1 Sure

[lsf37]

Cool, will go ahead with this.